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Photographic 

Sciences 
Corporation 


23  WEST  MAIN  STREET 

WEBSTER,  NY.  14580 

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L<P 


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CIHM/ICMH 

Microfiche 

Series. 


CIHM/ICMH 
Collection  de 
microfiches. 


Canadian  Institute  for  Historical  Microreproductions 


Institut  Canadian  de  microreproductions  historiques 


1980 


Technical  and  Bibliographic  Notes/Notes  techniques  et  bibliographiques 


The 
to  t 


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D 
D 
D 

D 


D 


n 


Coloured  covers/ 
Couverture  de  couleur 


Covers  damaged/ 
Couverture  endommagSe 


Covers  restored  and/or  laminated/ 
Couverture  restaurde  et/ou  pelliculifte 


Cover  title  missing/ 

Le  titre  de  couverture  manque 


I      I    Coloured  maps/ 


Cartes  gdographiques  en  couleur 


□    Coloured  ink  (i.e.  other  than  blue  or  black)/ 
Encre  de  couleur  (i.e.  autre  que  bleue  ou  noire) 

□    Coloured  plates  and/or  illustrations/ 
Planches  et/ou  illustrations  en  couleur 


n 


Bound  with  other  material/ 
Reli6  avec  d'autres  documents 

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□    Coloured  pages/ 
Pages  de  couleur 

□    Pages  damaged/ 
Pages  endommagdes 

I      I    Pages  restored  and/or  laminated/ 


D 


D 
D 


Pages  restaur6es  et/ou  pellicul6es 

Pages  discoloured,  stained  or  foxed/ 
Pages  ddcolordes,  tachet^es  ou  piqudes 


The 
pos 
oft 
film 


Ori$ 
beg 
the 
sior 
othi 
firsi 
sior 
or  i 


I      1    Pages  detached/ 


Pages  d6tach6es 

Showthroughy 
Transparence 

Quality  of  prir 

Quality  in^gals  de  I'impression 


I       I    Showlhrough/ 

I      I    Quality  of  print  varies/ 


I      I    Includes  supplementary  material/ 


Comprend  du  materiel  supplementaire 

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obtenir  la  meilleure  image  possible. 


The 
sha 
TIN 

whi 

Mai 
diff 
enti 
beg 
righ 
reqi 
met 


/ 


This  item  is  filmed  at  the  reduction  ratio  checked  below/ 

Ce  document  est  film^  au  taux  de  reduction  indiqu6  ci-dessous. 


10X 

14X 

18X 

22X 

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1 

^/ 

12X 


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28X 


32X 


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empreinte. 


The  last  recorded  frame  on  each  microfiche 
shall  contain  the  symbol  — ^  (meaning  "CON- 
TINUED"), or  the  symbol  V  (meaning  "END  "I. 
whichever  applies. 


Un  des  symboles  suivants  apparaltra  sur  la 
dernidre  image  de  chaque  microfiche,  selon  le 
cas:  le  symbole  —*"  signifie  "A  SUIVRE",  le 
symbole  V  signifie  "FIN". 


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method: 


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Lorsque  le  document  est  trop  grand  pour  §tre 
reproduit  en  un  seul  clichd,  il  est  film6  d  partir 
de  Tangle  sup^rieur  gauche,  de  gauche  d  droite, 
et  de  haut  en  bas,  en  prenant  le  nombre 
d'images  n^cessaire.  Les  diagrammes  suivants 
illustrent  la  m^thode. 


1 

2 

3 

1 

2 

3 

4 

5 

6 

SECOND  GK0L0c;,aLSi:KV£y  OF  .K.NAM-,.VANU. 


SPECIAL   KEPOirr 


ON  THB 


TRAP  DYKES  AND  AZOIC  KOCK.S 


OF 


SOUTHEASTEU.^  PEKXSYLVA. 


ANIA. 


Br 


T.  STERRY  HUNT. 


PART  I. 

HISTORICAL  LNTRODUCTION. 


Entered,  for  the  Commonwealth  of  Pennsylvania,  in  the  year  1878.  according 

to  aeis  of  Connrt'ss. 

liy  JOHN   U.  PEA  11  SI-:, 

Secretary  of  the  Board  of  Commissioners  of  Oeoloyical  Survey, 

In  the  olllce  of  the  Tiibrariiin  of  Congress,  at 

Wahiiisuton,  D.  C. 


1  •    ••    ;  

•   II    •  •  •*«ti*«« 


•  ;    ,",         •     SV«Jifi>ivi)c<l  anil  primed  by 
•'  1  .'  •  '.•.•'l-AN>:'fi.''ll.\l{l'.  •*tiit('  Prlntor, 


llnrrliibur^,  I'a. 


BOARD    OF    COMMISSIONERS. 


Hi.s  Excellency,  JOHN  F.  HARTRANPT 
AkioPaudee,     -    .     .    /"'^^■"^"■"^•-"'-to'f 
William  A.  Ingham       .  "    "    "    ' 

Hk.vry  S.  Eckkrt,    '..  "    "    '    "    ' 

He.vhy  McCoumick,    -.."""'' 

Jamks    iMACEAKLANE,    -      -  "      '      "      '      " 

JoJix  B.  Pkakse,     -     .  "    '     "    ■     - 

Jo8EPii  Wilcox,     -     .  "    '     "    "     " 

Hon.  Daniel  J.  Morrell,  -'"'■■ 
Henry  \V.  Oliver,     -  '    '    '    ' 

Samuel  Q.  Brown,'    -..,""'' 


llifBotti-.l,  HarrUbur^. 

HazletoiL 
Piiihidplphia. 
Heading. 
Harrisburo- 
I  owanda. 
PJiiladelphia. 
Pliiladeli)liia. 
Johnstown. 
Pittsburgh. 
Pleasantville. 


SECRETARY  OF  THE  BOARD 
John  B.  Pearse,     .    .    .  ^^^^IJ. 

"■■---    Philadelphia. 


Pj-^ter  Lesley, 


STATE 


GEOLOGIST. 


Philadelphia 


1878. 
ASSISTANT    GEOLOGISTS. 

Peksifor  Fbazer,  Jr.-Goologist  in  charge  of  the  Survey  of  York,  Adams, 

Lancaster,  and  Chester  counties. 
A  E.  LKHMAN-Toiiographioal  Assistant,  surveying  the  Soutn  Mountains. 
Fkei.eiuck  Prime,  Jr.-Geologist  in  charge  of  the  Survey  of  Lehigh,  North- 
ampton, Berks,  and  Lebanon. 
A.  P.  BERLiN-Topographical  Assistant,  surveying  the  Limestone  Valley  and 

Reading  Mountains. 
John  II.  DEWEEs-Geologist  in  charge  of  the  Survey  of  the  Fc^.ail  Ore  belts 

of  tlie  Juniata  country. 
Fbankmn  PLATT-Geologistin  charge  of  the  Survey  of  Clcarlield,  Jeirerson, 

Cambria,  Somerset,  Blair,  <fcc.,  &c. 
W.  G.  PLATT-Geologist  ia  charge  of  the  Survey  of  Indiana  and  Armstrong 

counties. 
R.  H.  SANnERS-Topogra{)lucal  Assistant  in  Blair,  Somerset,  Cumberland, iScc. 
I.  C.  White— Geologist  in  cliarge  of  tlie  Survey  of  Beaver,  Lawrence,  Mer- 
cer, ttc. 
J.  F.  Carll— Geologist  in  cliarge  of  the  Survey  of  the  Oil  Regions, 
H.  M.  Chance— Geologist  in  charge  of  tlio  Survey  of  North  Butler,  Clarion, 

&c. 
C.  A.  AsHBURNER— Geologist  in  charge  of  the  Survey  of  McKean,  Elk,  and 

Forest. 
C.  E.  B1M.IN— Geologist  in  charge  of  the  Survey  of  the  Seven  Mountams,  Ac. 

Andrew  Sherwood— Geologist  in  charge  of  the  Survey  of  Bradford,  Tioga, 

Potter,  Lycoming,  Sullivan,  and  Wyoming. 
F.  A.  Gentii— Chemist  and  Mineralogist  at  Philadelphia. 
A.  S.  McCbeath— Chemist,  in  charge  of  the  Laboratory  ot  the  Survey,  223 

Market  street,  Harrisburg. 
C.  E.  Halt.— Fossil  Zoologist,  in  charge  of  tlie  Museum,  and  of  the  Survey 

of  Bucks,  Philadelphia,  i\:c. 
Leo  Lesquereux— Fossil  Botanist,  Columbus,  Ohio. 

E.  B.  HABDEN-In  charge  of  Illustrations  for  the  Reports,  1008  Clinton  street, 
Philiidolphia. 

Chauleh  Am.en— In  charge  of  the  Collection  of  Records  of  Rtvilroad  and 
other  Levels,  Harrisburg. 

F.  W.  Forman— Clerk  in  charge  of  the  Distribution  of  Reports  from  the 
rooms  of  the  Board,  223  Market  street,  Harrisburg. 


E. 


J-ETTER 

BY  THE  STATE  GEOLOGIST 


To  tke  Governor  and  JIolroNX'""]^'  "^""^  '^'  ''''■ 
of  tke  Second  GeoUgT^ZlTof  "i  ^'"«'»'«-»-* 

-Inch  you  req„es  JDrTst^n '  ^r'"*"'  K<^P»^* 
Chemist  an<I  Minernlon-io.  \'  I^""/  ""nt-f„r  many  yeara 

ado    and  now  ProfS"' 'o^Geow'"^""' '""^^  °f  <S» 
lee  ,„„lo.y,  i„  Bosto„,_to  p.^'   e       '"  ">^  f-^'to'te  of 

Tlie  resolution  of  iXil  i,o,„  ,  ™  , 
specifies  the  object  ^"V-ar. >"-'''.  ^875,  and 
••eport  on  tlie  Trap  rocks  If  P        '^, ""'  «^--"nin.-'Oon  and 
°'  a;e  Board  being  ^J^eldTT""''^'''  '"«  Secreta  y 
Hnnt     At  the  n.ee,i„g'orNoV4  °""™"'"'™te  with  Dtf 
Ponod  t]>at  Dr.Hunthtdaorpted't,/:'  ""^  ^''''''■■^^y  ■•- 
Geologist  reported  that  Dr  IW  h  f  f  *  '  '"'"  "'«  S^te 
)"s  survey  in  Southern  Penning     '*'''f '^  commenced 
necessarily  involve  a  stuiW  theT  '':  '"''  "''"  "  «'<«'« 

Tlie  volume  in  hand  will  s,  ffll;    f,'"'"  ''°*^- 
necessity.  ""'  sufficiently  attest  to  this  evident 

The  survey  of  <-}i«  a 

Pe,msyU.„ir,  ,Lten:;;?,C,td  to  tf''"'''™ --1  Eastern 
gists  ot  the  regular  corps,  t"  w,t        ""'"^  '=°"'P'-''«'"  «eolo- 

^<J  i  rolessor  Fredprini-  r»  • 
faston,  the  topog^S™  )  ^i""  t'  °'  ^"^"^""e  College 
luro-Camhrian  slate  n^,  Seological  survey  of  tl  e  S?' 

""•'■■'  •->-  '»"•  aittrritfri 


viE. 


LETTER. 


rivers.  This  elaborate  survey  has  been  in  progress  under 
Prof.  Prime's  able  direction  since  the  beginning  of  the  sur- 
vey. The  second  volume  of  his  reports  of  progress  is  about 
to  issue  from  tlie  press,  and  his  lield-party  is  engaged  in 
finishing  the  southern  border  of  the  mountain-land,  includ- 
ing the  overlapping  edge  of  tlie  Trias. 

To  Professor  Persifor  Frazer  Jr.  of  Philadelphia,  was 
assigned  a  similar  instrumental  survey  of  the  Azoic  mass  of 
the  South  Mountain  in  York,  Adams,  Franklin  and  Cum- 
berhmd  counties  ;  including  the  Siluro-Cani})rian  limestone 
contact  on  the  northwestern  side,  and  the  Trias  contact  on 
the  southeastern  side,  with  an  enclosed  limestone  valley. 
Prof.  Frazer"  s  lines  however  traversed  the  wide  low-lying 
triangle  between  the  Soutli  mountains,  the  Susquehanna 
river  and  the  Maryland  state-line ;  occupied  by  a  broad 
belt  of  Trias,  by  two  belts  of  limestone,  and  a  still  broader 
belt  of  Azoic  slates,  of  unknown  relationship.  This  impor- 
tant and  minute  survey  has  been  going  on  since  1874,  and 
is  far  from  comph^tion  yet.  Prof.  Frazer  in  1877  continued 
his  personal  survey  of  the  York  county  limestones  and 
Azoic  slates  and  gneisses  into  and  over  the  whole  of  Lan- 
caster county,  his  report  of  which  is  nearly  ready  to  go  to 
press.  But  his  field-party  continues  the  slow  and  laborious 
work  of  mapping  the  South  mountains. 

To  Mr.  Charles  E.  Hall  has  fallen,  in  a  natural  way,  as 
the  geologist  in  charge  of  the  State;  Museum,  the  even  more 
difficult  task  of  unraveling  the  tangled  threads  of  that  skein 
of  Azoic  gneisses  and  slates  which  stretches  from  the  Dela- 
ware River  at  Trenton,  across  the  Schuylkill  between  Phila- 
delphia and  Conshohocken,  through  Chester  and  Delaware 
counties,  to  the  Delaware  and  Marvland  state-lines.  Sev- 
eral  thousand  hand  specimens  have  been  collected  and  ar- 
ranged in  the  museum,  for  study  and  comparison  ;  and 
every  exposure  of  rock,  however  insignificant,  is  not  only 
represented  in  the  cabinet-series  of  cross-sections,  but 
located  on  the  map.  A  long  stride  has  already  been  made 
towards  the  true  solution  of  the  jiroblem  of  our  Azoic  rocks, 
and  of  their  relationship  to  the  slate,  sandstone  and  lime- 
stone formations  which  overlie  them. 


LETTER. 


E.  vii 


la- 
la- 
ire 

iV- 


Meanwliile  many  microscopic  and  chemical  analyses  uf 
these  enigmatical  rocks  have  been  made  by  Dr.  Genth,  tlie 
Chemist  and  Mineralogist  of  the  Survey  ;  who  lias  also  paid 
great  attention  to  the  species  of  traps  collected,  and  will 
continue  to  make  a  special  study  of  that  subject. 

In  sui)port  of  the  assiduous  studies  by  these  gentlemen 
of  the  Azoic  rocks  in  their  respective  distri(!ts,  and  to 
further  the  success  upon  whicli  thej^  can  already  congratu- 
late themselves,  it  was  unquestionably  desirable  to  compare 
their  observations  and  conclusions  with  those  made  and 
reached,  by  geologists  outside  of  the  State,  in  the  Azoic 
regions  of  New  Jersey,  Northern  New  York,  New  Eng- 
land, and  especially  of  Canada.  No  better  plan  could  have 
been  adopted  to  reach  this  end  than  to  invite  so  distin- 
guished a  student  of  Azoic  geology  as  Dr.  Hunt  to  visit 
those  districts  of  our  survey  which  seemed  to  correspond 
with  those  in  the  north  among  wliich  he  had  spent  the  best 
part  of  his  laborious  and  successful  life  ;  and  no  book  could 
be  more  useful  tlum  one  in  which  he  should  collate  all  the 
known,  supjjosed,  and  susi)ected  facts  of  American  Azoic 
geology  ;  with  all  the  accepted  conclusions,  and  proposed 
hypotheses,  pul)lished  on  the  subject  by  the  most  eminent 
geologists  of  the  last  half  century  in  Europe  and  America, 

We  owe  therefore  a  debt  of  gratitude  to  Dr.  Hunt  for 
this  historical  monograph,  which  will  supply  a  dee])ly  felt 
deficiency  in  the  literature  of  our  science.  It  is  a  treasury 
of  notes  and  suggestions  of  the  greatest  value  t(j  the  geolo- 
gists of  Pennsylvania,  and  of  other  States,  working  in  such 
districts  as  are  occupied  at  the  surface,  or  are  underlaid  at 
moderate  depths,  by  the  Cambrian  and  sub-Cambrian  for- 
mations ;  although  no  linal  demonstration  has  been  ncrAmi- 
jilished  by  the  author  of  those  problems  of  superposition, 
unconformability,  and  identification,  at  which  so  many 
geologists  are  still  half  despairingly  at  work.  But  his  opin- 
ions of  the  probable  final  solutions  of  these  problems  will 
reenforce  their  own,  wdien  they  agree,  and  lead  to  fruitful 
discussions  when  they  disagree. 

Dr.  Hunt's  views  on  one  or  two  points,  like  that  of  the 
relationships  of  the  slates  of  the  great  valley,  are  i^eculiar 


i  ''?! 


viii  E. 


LETTER. 


to  himself,  and  are  not  in  accordance  witli  the  views  of  the 
Pennsylvania  geologists  either  of  the  First  or  Second  sur- 
veys. But  it  is  of  real  importance  to  obtain  the  circum- 
stantial statement  of  his  opinions  given  in  this  report  The 
linished  instrumental  survey  of  these  slates  and  unde.  ying 
mngnesian  (Siluro-Cambrian)  limestones  in  Blair  county, 
iind  the  rapidly  advancing  surveys  of  the  same  outcrops  in 
Clinton,  Milllin,  Cumberland,  Dauphin,  and  Lebanon  coun- 
ties, with  the  close  instrumental  surveys  at  the  Schuylkill, 
Lehigh,  and  Delaware  water-gaps,  confirm  our  opinion  of 
the  correctness  of  the  interpretation  made  by  tlie  geologists 
of  the  First  survey. 

It  is  still  somewhat  premature  to  dogmatize  about  the 
Taconic  system  ;  as  it  is  impossible  yet  for  any  competent 
judge  to  express  a  positive  opinion  respecting  the  value  of 
such  terms  as  Montalban,  Norian,  &c.,  in  Pennsylvania; 
seeing  that  the  closest  scrutiny  during  the  last  two  years 
has  not  availed  even  to  make  it  certain  whether  the  gneiss 
belt  underlmB  or  ooerlies  the  mica-slate  belt  in  Bucks, 
Montgomery,  Philadelphia  and  Chester  counties  ;  although 
Mr.  Hall  has  made  it  almost  certain  now  that  the  Edgehill 
rock  lies  at  one  locality  unconformably,  and  in  a  synclinal, 
upon  the  gneiss,  and  that  the  Chester-valley  limestone,  of 
later  age,  occupies  this  same  synclinal. 

Since  Dr.  Hunt's  observations,  made  two  years  ago.  Pro- 
fessor Frazer'has  worked  out  the  important  section  along 
the  Susquehanna  river,  and  determined  the  great  anticlinal 
uplift  across  Lancaster  county,  with  gneiss  in  its  axis, 
throwing  off,  on  opposite  dips  to  the  north  and  south, 
many  thousands  of  feet  of  Azoic  slates,  all  of  them  older 
than  the  Cambrian  (?)  calcareous  slates  which  underlie  the 
mngnesian  limestones.  And  Professor  Prime  has  found 
graphitic  gneiss  with  limestones  in  the  (Laurentian  ?)  uplift 
north  of  Bethlehem.  Light  seems  fast  breaking  in  upon 
this  dark  region  of  our  geology. 

Respectfully  submitted, 

J.  P.  LESLEY. 


E.  ix 


PREFACE 

BY  THE  AUTHOR. 


This  volume  owes  its  orioi,,  t 
s  oners  of  tJie  Second  Geolol.!  \"'1'"'"'  »'  t'-e  Commis- 
fat  the  author  should  prl^r.  ,  "7  "''  P«"»^vlv.„ia 
that  State  with  especiaS  n^'i'"!?  '!'«^r'°'"^  '" 
Irap  Dykes  and  tl,e  Iron  Ores  T hi  ll  '"  ^°*'*>  ">« 
of  these  several  points  as  iriin'.^  "''''qi'ate  discussion 

eration  of  some  of  the  leasT   „  t'''"',"'"^'^^''  "'«  «>■'«''- 
tions  in  geological  scfence  """  "'™'  ''^''f*'!  q»es- 

«ylvania,  was  restricted  to  the  un,  '  ^'■'°'°°y  "^^  ?««"- 

line  scljists,  occupving  a  hot  f  '  P°'"™  '"  "'«  "''J'^tal- 
paleozoic  sediment;  a,rd  t  a  mo  ,  ^l"'™  ""^  ""cO-staliine 
«'..ch  he  gave  the  name  o  hX;  ""t;' »"r'''"'^  '^™^  *« 
ever  by  him  declared  to  be  in  1  '  '"'"-''■  '^'^  '">»'- 

termediate  or  Azoic  series  »  T?  T'^''  '"  '"«  "'«  in- 
distinguish,  lithologicaliv  hefJ  ",''"'■  "  ™P"«»iW.^  to 
Hypozoie  and  Azoic  S  ':!  Z t^M  'T  '""'  """«' 
'^-.•andWltituey.whichrr^!:;^^--- 


xE. 


PUEFACK. 


included  all  the  rocks  below  the  fossiliferous  sedimentary 
strata,  unl  has  been  shown  by  subsequent  investigations  to 
comprise  several  distinct  stratified  terranes. 

A  large  portion  of  the  rock-masses  associated  with,  and 
in  fact  forming  an  integral  part  of  this  Azoic  system,  were, 
by  the  writers  last  named,  included  in  the  category  of 
igneous  or  erupted  rocks.  Such  were  the  gneisses,  the 
quartzose  or  j)etrosilex-porphyries,  the  greenstones,  the 
serpentines,  and  the  masses  of  magnetic  and  spt;'ular  oxyds 
of  iron.  Othei',  and  contemporary  writers  added  to  this 
list,  labradorite  or  hypersthene-rock,  together  with  certain 
crystalline  limestones  and  quartz-rocks.  Later  restnirches 
have  however  led  most  geologists  to  the  conclusion  that  by 
far  the  greater  jjart  ol  ihese  so-called  igneous  rocks  are 
stratified  or  indigenous  masses,  which  are  not  to  be  con- 
founded with  the  distinctly  intruuv.^d  exotic  rocks,  such  as 
the  true  granites,  the  trachytes,  dolerites,  etc.  ;  nor  yet  with 
the  concretionary  veinstones  which,  like  these,  traverse  the 
stratified  rocks. 

It  was  evidently  a  question  of  tiie  first  importance  in  the 
proposed  investigation  to  draw  the  lines  between  the  three 
orders  of  crystalline  rock-masses  Just  defined,  and  to  deter- 
mine whether  a  so-called  trap-dyke  is  a  foreign  mass,  which 
has  been  injected  among  previously  formed  neptunean 
strata,  or  is  itself  an  oi'iginal  part  of  the  si  ratified  forma- 
tion. The  same  question  arises  with  regard  to  the  de])osits 
of  magnetic  an(i  sj)ecular  oxyds  of  inm,  which  abound  in 
the  crystalline  rocks,  and,  within  the  last  few  years,  have 
come  to  be  c(msidered  not  as  intruded  but  as  indigenous 
masses.  The  change  of  views  on  all  these  points  which 
has  taken  place  within  a  generation,  constitutes  a  complete 
revolution  alike  in  g(M)geny  and  in  geognosy. 

Otliei',  and  not  less  im[)ortant  (piestions  aiise  in  this  con- 
nection, with  regard  to  Ihe  ohler  p:ileo:'.oic  formations  and 
their  relations  to  the  crystalline  terranes.  These  relations 
have  been  tin;  subject  of  much  misconcei)tion,  and  many 
contradictory  hypotheses,  and  have  moreover  important 
bearings  on  the  ])i'oblems  })roposed  in  this  report.  To  pre 
jiare  thesf  udeiit  foran  adecpiate  discussion  <»f  all  tliese  ques- 


PUEFACE. 


E.  xi 


tions,  it  was  felt  that  notliing  less  than  a  historical  and 
critical  review  of  tlie  progress  of  our  knowledge  of  the  older 
rocks  of  North  America  would  suffice. 

The  publication  of  Maclure's  map  and  description,  in 
1817,  marks  the  beginning  of  sixty  years  of  great  activity 
in  the  study  of  American  geology,  the  chief  results  of 
which,  so  far  as  they  bear  on  the  crystalline  and  other  pre- 
Sihirian  formations,  it  has  been  the  author's  ol)ject  to  set 
forth  in  Chapters  II- V  of  the  present  work.  The  fact  that 
for  more  than  one  half  of  this  time  he  has  been  a  constant 
laborer  in  different  parts  of  the  field,  may  help  to  justify 
him  in  attempting  the  task,  lie  has  aimed  at  as  great 
conciseness  and  brevity  as  is  consistent  with  clearness  of 
statement,  but  trusts  that  the  present  sketch  may  serve  as 
the  basis  of  a  more  complete  and  extended  history  of  the 
Pre-Silurian  Rocks  of  North  America,  which  it  is  his  pur- 
pose to  prepare. 

The  succeeding  chapters  of  this  report  will  be  devoted  to 
the  consideration  of  the  decay  of  crystalline  rocks,  and  its 
geological  importance,  and  to  the  nature  and  origin  of  the 
various  deposits  oi  iron-ores.  They  will  be  followed  by 
the  author's  observations  on  the  geology  of  southeastern 
Pennsylvania,  and  the  elucidation  of  many  of  the  questions 
raised  in  the  introductory  chapter.  As  the  temporary  ab- 
sence of  the  author  from  the  country  will  retard  for  som(» 
months  the  completion  of  the  work,  it  has  been  thought 
best  to  publish  separately  the  first  five  chapters,  which 
conclude  the  historical  and  critical  part,  so  far  as  regards 
American  stratigraphy.  An  index  will  accompany  the 
completed  report,  and  meanwhile  the  present  jjortion  is 
provided  with  an  analysis  of  the  chapters,  which,  it  is 
hoped,  will  help  to  recommend  it  to  students  of  American 
geology. 

T.  S.  H. 

BosTON^,  Mass.,  June  1,  187S. 


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E.  xiii 


CONTEIS^TS. 


CHAPTER  I. 

Introduction  to  the  GeoijOoy  of  Southeastern  Pennsy'lvania. 

01)jcct  and  plan  of  this  report,  page  1.  Relations  of  the  so-callod  trappoan 
rocks,  1.  Ilypozoic  and  Azoic  systems  of  H.  D.  Rogers,  2.  Tie  distinguisiios 
three  groups  in  tlie  crj'stallino  strata,  3.  His  spb-division  of  tlie  Iowhm-  Taloo- 
zoic  into  Primal.  Auroral,  and  ^Matinal,  4.  Distribution  of  the  llypozoit! 
rocks;  three  gnoissic  districts,  C>.  The  Blue  Ridge  in  southern  Pennsylvania, 
7.  Errors  in  the  geologiojil  map  of  Pennsylvania,  7.  The  nortliorn  and  mid- 
dle gneissic  districts;  their  Laurentian  ag<i,  8.  Soutiieast  ilip  of  tlie  strata 
along  the  South  Mountain,  0.  The  soutliern  or  Philadelphia  gneissicuiistrict; 
its  three  divisions,  1(».  Micaceous  and  liornhlomlic  strata,  10.  Sj'cnites, 
greenstones,  and  iron-ores,  11.  Steatite  and  serixnitino  lielt,  12.  Massive 
gneisses  and  crj'stalline  limestones,  12.  Prevailing  northwest  dip  of  strata  in 
the  southern  district,  13.  The  gneisses  of  its  nortlierii  jiortion,  11.  Its  mag- 
nesiau  strata,  and  tlie  supposed  igneous  origin  of  serpent  iiics,  1").  Crystalline 
scliists  at  the  base  of  the  Paleozoic,  17.  Tlio  Azoic  ami  Palooz:>ic  systems,  17. 
Crystalline  strata  south  of  the  Susquelianna,  called  altered  Primal,  18.  Rogers 
on  the  igneous  origin  of  (luartz  and  crystalline  limestones,  10.  Strata  called 
altereil  Mosozoio  sandstone,  19.  The  various  formations  siipi)osed  by  Rogers 
to  have  undergone  nietamorphism,  20.  E;ustorn  Pennsylvania  on  Logan's 
geological  map,  22. 


CHAPTER  IT. 

Historical  Sketch  oi-  American  Pre-Silurian  OEOLoay. 

Mucl lire's  geological  map  of  the  United  States,  1817,  p.  23.  His  Primitive 
and  Transition  mcks,  24.  Eaton,  his  fTeological  Text-book,  1832,  24,  His  five 
great  ternar;\-  groups  of  strata,  2.").  The  Primitive  serii-s  of  Eaton,  2;').  Tlie 
gneisses  of  the  Macomb-Mountain  range,  and  of  tlie  Now  York  Higlilands, 
distinguished  from  those  of  New  lOngland,  2(i.  The  Transition  and  T.owcr 
Secondary  series,  2(>.  The  l^pper  Secondary  series,  and  the  Coal  measures,  27. 
Tlio  Transitiiin  Argillite,  and  the  I'irstand  Second  <iraywackcs,  28.  Distribu- 
tion of  tlie  First  or  'I'raiisition  <Jraywa(!k(!  in  eastern  New  York,  29.  Views 
of  H.  D.  Rog(!rsin  1840.  30. 

(icological  survey-  of  New  York,  ls;',7-1842,  30.  I'hnmons  on  tlie  geology  of 
tho  iiortliern  or  sei'ond  distri(!t,  1812;  the  Now  Yorlv  Transition  system  ;  Ciuun- 


xiv  E. 


CONTENTS. 


plain  and  Ontario  divisions,  31.  Tlie  Transition  Oraywacke  of  tho  Champlain 
and  Hudson  valleys,  31.  IIudson-River  slates  and  Loraino  shales,  32.  The 
Taconi(!  system,  as  defined  by  Euinions  in  1842,  32.  Mather  on  tho  southern 
or  first  district  of  New  York,  1843;  the;  Taconic  d(;elar('d  identical  with  the 
(•lianiiilaiii  <livisioii,  33.  Tlie  Hudson  axis  as  delined  by  Matlier,  33.  Its  re- 
lation to  tlie  Transition  series  of  I']aton,  34.  The  disturi)ed  roj^ion  eiust  of  the 
axis,  35.  Eastern  dips,  and  inverted  succession  of  strata,  3").  Matl)er  on  the 
Sliawaiif^unlv  riui^c,  and  on  a  similar  (Jraywacko  series  in  eastern  New  York, 
extending  into  Vermont  and  New  .Jersov,  30.  Tlio  flreen  Pond  Mountain 
range  in  New  Jcrao;  30.  Conclusions  of  Horton  as  to  tlio  stratigraphical  re- 
lations of  tliis  series,  37.  It  is  referred  by  Mather  to  tlie  Ontario  division,  37. 
Tlie  western  limit  of  EmiiKJiis'sTaeonic  undetined  in  1842,  37.  Mather  on  the 
Cliamplain  ago  of  tiio  Taoonie,  38.    Similar  views  of  tho  Messrs.  Rogers,  38. 

Tlie  crvstalliiK^  formations  divided  liy  Matlier  into  Primary  and  Metamor- 
\)hU',  38.  Distribution  of  tlie  Primary;  tlie  Highlands  of  tho  Hudson,  38. 
Mather's  two  Mctainorpliic  groups,  39.  First  group,  east  of  the  Highland 
range,  suppc)sed  by  Iiim  to  be  altera  '  ('iiain(>Iain  strata,  40.  His  second 
M(!taniorpliie,  including  part  of  tlie  1  limary,  40.  Primary  limestones  de- 
clared to  bo  altered  Paleozoic,  41.  .Similar  views  held  Ijy  Nuttall  in  1822,  and 
adopted  by  II.  D.  Ilt)gers  in  1812,  41.  Rogers  on  tlie  supposed  alteration  of 
tlie  Transition  limestones,  42.  Mather  on  the  (sruptive  origin  of  some  crystiil- 
lino  limestones,  43.  Emmons  on  the  Primary  rocks  of  northern  New  York, 
43.  ("rysialline  limestone,  serpentine,  liyperstlunie-rock,  and  iron-ores,  re- 
garded as  unstratilied,  43.  lOmmoiis  icjccts  the  vicnvs  of  Nuttall  and  Mather, 
and  maintains  tlie  igneous  origin  of  gneiss  and  otlit^r  stratilie(l  (irystallino 
ro<0<s,  43.     lIy]i(irstheno  or  laljradorite-rock  of  Essex  county,  TTew  York,  44. 

lOmmons  on  the  Taconic  system  in  1840;  lie  extends  its  limits,  45.  Declares 
it  uneoiiformably  ovf^rlaid  by  the  New  York  system,  and  of  Ijower  Cambrian 
age,  45.  Its  gi'ogiaphieal  distribution,  45.  Relations  of  tho  Loraino  shales  to 
the  Taconic  slates,  45.  Stratigrai)hieal  sections  in  eastern  Now  York,  40.  The 
(Jraywacke  series  of  this  region,  previously  placed  above  the  Trenton  lime- 
stone, now  referred  to  the  Calciferous  sandroclc,  47.  Emmons's  change  of 
views  from  1842  to  1840,  47.  Distributi<m  of  this  Graywacko  series,  47.  Its 
relations  to  the  T'tica  and  Loraine  formations,  48.  Three  discordant  series  of 
uner^'stallino  rocks  in  the  Hudson  Valh^y,  4!t.  Relations  of  those  to  the  Tren- 
ton limestone,  and  doiiosition  of  tho  members  of  the  Cliamplain  division,  49. 
Relations  of  the  Utii^a  and  Loi'aine  formations  t<i  older  rocks,  50.  (For  a 
further  disiaission  of  these  relations,  and  for  tlio  oliservationsof  Conrad  and 
Vanuxom,  soo  chapter  IV,  pages  144-140.) 

Emmons's  American  Ceology,  1855;  his  revised  conclusions,  50.  Grapto- 
lilli^  slates  of  the  Taconic,  51.  Succession  of  the  Taoonio  rocks  in  1840,  51. 
Their  division,  in  1855,  into  liower  and  Upper  Taconic,  52.  Emmons's  Manual 
of  Geology,  1800, 53.  The  liOwer  T.uionic!  described  ;  section  of  it  in  Berkshire 
county,  Mass.,  53.  TIh?  Upper  Taconic  series  descrilxHl,  53.  Section  of  it  in 
Washington  county.  New  York,  54.  Its  a|)parently  inverted  order  explained 
by  successive  dislocations,  with  uplifts  on  tlie  east  side,  55.  Thickness  and 
distriliution  of  the  I'pper  Ta(M)nic,  ,55.  Tliis  series  unrecognized  in  1842,  not 
being  clearly  (listiiiguished  from  tho  Secondary  Graywacko,  55,  Upper  Ta- 
conic in  Vermont,  and  near  Queltec,  5(t.  Apjiartint  contradictions  and  ob- 
scurity in  tho  writings  of  Emmons,  57. 

'flic  Proti'an  Ciilcifcnuis  s;indrock,  or  Upper  Taconic  series,  57.  Tlio  Rod 
sandrock  of  Vermont,  58.    It  is  referred  by  Adams,  in  1840,  to  tho  Modina 


CONTEXTS. 


K.   XV 


formation,  .00.  Tlio  Keil  limestones  of  Winooski.  placed  hy  W.  15.  Rogers,  in 
1&>1,  above  the  Medina,  iSO.  C.  11.  Ilitehcook,  in  ISiJO,  refers  the  Lower  Taconie 
limestones  to  tiio  I'pper  Silurian  or  Devonian,  (iO.  Adams,  in  ISli!.  conjectun's 
the  Lower  Taconi(!  series  to  l)e  altered  lied  saii<lrock  and  \Vinooski  lime- 
stone, 60.  Mather,  having:  maintained  tlie  erystalline  rocks  of  western  New 
England  to  b(>  tiie  mciamorphie  ("hamplain  division,  tlie  Messrs.  Rogers,  in 
1S44,  (»nci  ive  the  Wiiiie  Mountains  to  be  tlie  suoeeeding  Ontario  division 
metamorphosed,  (52.  Su[)posed  organic  remains  of  tlie  Clinton  lormalion 
therein,  ('>-.  C.  T.  .Ji'ckson,  in  l.S4t),  as.serls  tiie  Primary  ago  of  the  White 
Mountains,  but  reganLs  tlie  (ireen  Mountains  and  the  Lower  Taconie  rocks 
OS  altered  Canibrian  and  Silurian,  (V2. 


lan 

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39  of 

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Red 
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CHAPTER  Til. 

History  oi"  Amkkhan  Pre-Sii.uuian  Geology,  Conpinued. 

Geology  of  Canada;  observations  of  Eaton,  Enunon.s,  and  others,  (i:{.  Geo- 
logical survey  of  Canada  begun,  1S42,  ()4.  Early  statements  of  Logan  as  to 
the  Primary  and  Transition  rocks,  ti4.  Murray,  in  l^i;!,  calls  llic  Primary  of 
western  Canada.  Metamorphic,  (Jo.  C(mne(!tion  of  the  author  with  the  survey, 
in  1847,  and  his  subsequent  relations  tlier(nvith,  (id.  I'^.xploration  of  the  Ottawa 
valley  by  Logan;  its  gneisses  described,  in  1S47,  as  ^^etamorphi(•,  (Hi.  Their 
division  into  a  lower  an<l  an  upper  group,  (i7.  A  younger  series  of  chloiitic 
Hchists  on  Lake  Temiscaniing,  (7.    Overlying  Sihirian  limestones,  (17. 

Logan  and  Murray  on  T,ake  Superior ;  report  in  1847,  (iS.  An  older  gneissie 
series,  and  a  Aounger  chloritic  series,  with  greenstones,  (iS.  Two  ovcrl,\iiig 
vol(?!uiic  formations,  (iS.  Tlu^  upper  of  these,  the  Copper-bearing  trajjpcan 
and  amygdaloid  series,  (i9.  Regarded  as  older  than  the  Potsdam  .sjuidstono, 
(19.  Murray  on  tho  chloritic  grcienstone  series,  70.  Tjogan.in  1S4S,  attempts  its 
identilicjition  witli  the  Copper-bearing  trappean  s(>ries,  70.  Similar  views 
afterwards  held  by  Rivot,  and  by  Dawson,  71.  The  ancient  gneissie  grouj) 
called  liaureiitian,  in  ]S."i4,  72.  Th(!  name  of  Iluronian  given  to  both  the  <'lilo- 
ritiir  greenstones  and  the  copjier-bcariiig  trappean  series,  in  1S,V),  7U.  Tin,'  1  lu- 
ronian  then  supposed  identical  with  FiOwer  Cambrian,  72.  TiUter  views  of 
Dr.  Rigsby,  7;?. 

Foster  and  Whitney's  reiiort  on  Lake  Superior,  1851,7.'}.  Tlu;ir  geological 
cla.ssi(i(ration,  7."5.  The  greenstones,  serpt^ntines,  and  iron-ores  clas.sed  with 
tlic  igneous  rocks,  7S.  Their  Azoic  system  inciludes  both  tlu;  ancient  gneissi's 
anil  tlie  chloritic  greenstone  scries,  (Laurcntian  and  Ilnroiiiaii,)  74.  Rocks 
of  Keweenaw  Point,  and  of  the  Rohemian  Mountains,  7").  .Fasper  and  (juart- 
zijso  porphyry  of  the  latter,  and  of  the  Porcui)ino  Mountains,  7.").  Views  of 
Rivot  in  is.),"),  7(i.  He,  like  Logan,  regards  the  chloritic  greenstones  and  the 
tnippean  rocks  as  one,  and  denying  the  eruptive  nature  of  the  latter.  imIIs  the 
whole  altered  I'aleozoie,  77.  The  ancient  gneis.ses  supposed  by  him  to  bo 
eruptive  granites,  77.  Tho  conglomerates  of  the  Copper-bearing  series,  78. 
Rivet's  extension  of  the  doctrini'  of  nietaniorphism,  7S.  Wliitne.X',  in  l.S.")7, 
rejects  the  ilistiiiction  of  Laureiiiian  and  Iluronian  as  parts  of  his  A/.oie  .sys- 
tem, 79.  Ho  maintains  tlie  distin(!tness  of  tho  Copper-bearing  series,  whic^li 
he  includes  in  the  I'otsdam,  79.  Murray's  studies  of  the  Iluronian  rocks. 
)8i54-lH()0,  80.     In  the  Geology  of  Canada,  18(13,  the  name  of  Iluronian  is  re- 


xvi  E. 


COXTKNTS. 


stricted  to  the  cliloritic  greenstones,  then  called  the  Lower  Copper-bearing 
series,  80.  TIio  trapiioaii  rocks,  with  native  cupper,  nialvo  the  Upper  Copper- 
bearing  series  of  Loj^an,  Si.  Tlio  siiijposfd  paleozoio  age  of  tiiis  series,  82. 
The  overlying  simdstono  conceived  to  bo  of  the  age  of  the  Cliazy,  82. 

Green-Mountain  or  Xotre-Danio  range  ;  its  extension  in  eastern  Can.ada.  SS. 
Erroneous  views  regarding  it  given  by  geological  maps,  83.  Distinction  of 
crystalline  and  uncrystalline  roclis  in  the  region,  8;{.  Tlio  (ias[)6  sandstones 
and  lijneslones,  84.  Upjx-r  Taconii;  Argillites  and  riraywacke,  or  lludson- 
Rivcr  group,  in  esistern  Canada,  S").  They  are  placed  in  tlic  upper  part  of  the 
Cliami)lain  division,  8.").  (-rystalline  roclcsof  tlie  Notre- Danio  range,  S,").  Thoy 
are  declared  U)  bo  altered  Iludson-lliver  group,  8(5.  .Secti<in  from  the  St.  Law- 
rence, by  the  St.  Francis,  to  tlie  hornblendic  and  granitic  rocks  in  Vermont, 
80.    These  are  supposed  Ijy  Logan,  in  1S49,  to  Ijo  altered  Devonian,  87. 

The  Upper  Taconic,  or  IIudson-River  group,  from  Lake  Champlain  t<» '  !asp6, 
87.  Supi)osed  to  bo  younger  tiian  the  Trentf)n  limestone,  88.  Inversi.  as  and 
southeast  flips  of  the  scries,  89.  Tlie  Pillar  sandstones,  90.  Suiidivisions  of  the 
group,  90.  Cliloritic  sandstones;  tlio  false  conclusions  from  tlieir  composition, 
92.  Greenstones  and  amj-gdaloids,  witli  copjjcr,  93.  Copper-ores  witli  lime- 
stones, at  Actonvale,  and  elsewhen^  in  tiie  series,  93.  U(;asons  for  placing  the 
Graywacko  series  in  Canada  aljove  the  Trenton,  94. 

Early  studies  of  Bigsby,  in  1827,  94.  Studies  of  Bayfield,  184.J,  95.  Exist- 
ence of  two  series  of  sedimentary  rocks  near  Quebec,  9().  Dislocation  of  the 
Trenton  limestone  at  Montmorenci  Falls,  9fi.  liOgau.  in  18").'),  adopts  Matiier"s 
view  of  the  Hudson  axis,  whi<rh  lie  attempts  to  trace  ti>  the  St.  Lawrence,  97. 
The  Ujiper  Taconic  first  named  the  Quebec  formation,  97.  Its  graptolites  de- 
scribed l)y  Hall  in  18,55,  98.  Logan  on  the  lied  sjuidrock  of  Vermont,  98. 
Trilobitic  fauna  of  Point  Levis  discovered,  185(),99.  Fauna  of  the  Phillipsburg 
limestone:  studies  of  Billings,  99.  Logan,  in  I'^i'd,  adopting  the  view  of  lOm- 
mons,  places  tiiese  rocks  l)elow  tlie  Trenttju,  ItK).  Logan's  letter  to  Barrande, 
100.  Tlie  Upper  Taconio  now  called  the  Quebec  group ;  its  division  into  Levis, 
Lauzoii  :ind  Sillery,  101.  These  divisions  ik'scriljed,  102.  Tiic  author,  on  the 
dolomitfisand  limestones  of  Point  Levis,  103.  Tiie  striiclurcMif  Point  I^evis  do- 
scribed,  105.  The  distribution  of  the  organic  remains  l\wvo  found.  lOi!.  The 
section  on  Orleans  Island,  10(5.     Billings  on  the  Levis  fauna,  107. 

The  fauna  of  the  Rod  sandrock  of  Vermont,  108.  Fauna  from  tlie  straits  of 
Bellislo,  108.  The  rocks  of  Bonne  and  Pistolet  Bays,  Newfoundland,  109. 
Paleontological  deductions  of  Hilliiigs,  110.  His  suiidivisions  of  tlie  fossilifer- 
ous  strata.  111.  Tlie  formation  holding  Paradoxides,  112.  Tlie  so-called  Lower 
Potsdam  formation,  112.  Various  fauna.s  known  in  tho  Upper  Taconic  or  Quo. 
bee  series,  113.  Supitoseil  relation  of  the  Sill(>rv  sandstone;  views  of  Bil- 
lings and  liOgaii,  113.  Conclusions  of  the  author  iis  to  the  (Quebec  section,  114. 
Probable  inversion  of  tho  series,  114.  Its  rocks  compared  with  tho  Tremadoc, 
Arenig  and  Menevian  of  Wales.  115. 

Logan  on  the  stratigraphy  of  eastern  Canada.  Ih!.  The  fossiliferous  strata 
of  Farnham,  117.  Probable  succession  of  tho  members  of  tho  Quebec  group. 
117.  Views  of  Hall,  in  1802,  as  to  the  relations  of  ihe  Hudson-River  and  Lo- 
raino  forniiitions,  118.  Wing  and  Billings  on  the  fossiliferous  rocks  of  Ver- 
mont, no.  Logan  on  inversionsof  strata  in  this  region,  120.  Logan  and  Hall, 
in  1863,  on  the  Graywacke  and  Argillitc  of  the  Hud.son  valley,  120.  Relations 
of  these  older  fossiliferous  roi^ks  totlie  Trenton,  rticaand  Loraine  formations, 
120.    The  so-called  Hudson  anticlinal  axis,  now  supposed  by  liOgiin  to  be  a 


CONTENTS. 


1^  •  • 

'..   XV 11 


great  lin(>  of  fracture  and  iijilift,  121.    Logan's  hyiv)tli09is  to  explain  these  im- 
agined stratigrupliioal  relations. 

Evidences, in  the  Atlantic;  lieit,  t)rstratigrai>lii('al  non-conformity  in  paleozoic 
and  mesozoic;  times,  IJI}.  Supposed  uneoiiformity  at  the  iiaso  of  the  Trenton. 
123.  Till'  ('hazy  lormation  in  the  Ottawa  basin,  and  the  Muliawi..  valley,  124. 
Deposition  oltlie  Trentmi  limestone  on  pre-Caiiilirian  rocks,  121.  ('i>niinental 
movement,  with  submergence,  immediately  preceding  the  Trenton  period, 
12.'>.  Its  relation  to  the  u|)pcr  members  of  the  Champlain  division,  12;").  The 
boundary  belwecin  these  and  the  ITpper  Taeoiiic,  not  an  antii'liiial  axis,  nor  a 
lino  of  fracture  and  uplift,  but  one  of  contact  between  discordant  series,  12»i, 


CHAPTER  IV 


of 
09. 
^'or- 
Iver 
lue. 
V.il- 

IH. 

(oC, 

kta 
jup. 

|liO- 

,'er- 

iall, 
Ions 
l)ns, 
lie  a 


The  Ca-mbrian  Rocks  of  Europk  and  Amkrica. 

The  lower  paleozoic  rocks  of  Wales,  128.  The  Cambrian  series,  as  delintd 
and  divided  by  Sedgwick,  128.  Portions  of  it  wrongly  included  in  the  Silu- 
rian, 129.  Sihiro-Canibrian,  and  Upper  and  Lower  Camljrian,  delineil,  129. 
The  latter  divisions  in  Wales,  130.  Fauna  of  the  Lower  Cambrian,  130.  Silu- 
rian and  Cambrian  seriesof  Sweden,  130.  FiK-oidaland  l'>>|)hytonsiindsti(nes; 
their  organic  forms,  131.  Kjorulf  on  Lower  and  I'pperTaeonic,  and  Silurian, 
in  Norway,  131.  Cambrian  of  Russia  and  Uohemia,  132.  Stratigraphical 
range  of  Cambrian  organic  forms,  133.  Tlie  various  graptolitic  horizons 
known  in  lOumpi',  133. 

The  Potsdam  sandstone  of  the  NeM-  York  series,  134.  The  Calciferous  sand- 
rock;  a  dolomit<'  with  gypsum,  13.').  Organic!  remains  of  the  Potsdam;  Sco- 
lithus  Canadensis  of  l>illliigs.  i:>.">.  S(!olitlms  linearis  of  Hall,  its  history,  13t>. 
The  transversely  grooved  Scolithus  of  the  Primal  .s;indstone,  13".  The  aiitlior 
on  the  Scolithus  of  Port  Henry,  New  York,  139.  The  Chazy  formation  ;  its 
straligia[ihical  relations,  i:'.!).  The  St.  Mary"s  sjindstone  >.f  Lake  Supcsrior,  140. 
The  liower  Magnesian  limestoTio  of  Wisconsin,  141.  Its  associated  glau(!onite, 
141.  The  St.  Peter's  or  Chazy  .s;uidstone,  142.  The  Trenton  limestone,  tiie 
Galena  or  Upiier  Magnesian  limestone,  and  the  Cincinnati  group,  of  the  Mis- 
sissipjii  valley,  142.  The  Potsdam  sjuidstoneof  this  riigirin  ;  three  stages  in  its 
fatnia  defined  by  Hall,  143.  The  ('ambrian  rocks  of  Missouri,  143.  Their 
litliological  dissimilarity  to  their  eciuivalents  in  the  Ea.st,  144. 

Cambrian  rocks  of  the  third  or  central  district  of  New  York,  144.  Early 
observations  of  Conrad,  144.  Vanu.xem  on  the  Puliuski  or  Loranu;  shales,  the 
upper  member  of  the  Hudson-River  group,  144.  Its  lower  member,  the 
Frankfort  .slates,  or  the  Iludson-Kiver  slates  of  Mather.  1  !.">.  These  two  divi 
sions  distinct  in  Pennsylvania;  the  latter  a  partof  the  Taeoni<;  of  Emmons,  14.".. 
The  Oneida  conglomerate,  14C.  Disappearance  of  the  Pulaski  shales  to  the 
southeast,  in  the  Mohawk  valley.  14().  Thinning-out  and  disappearance  of  the 
Trenton  limestone  iu  the  same  region,  14(5. 


bE. 


xviii  E. 


contp:nts. 


CHAPTER  V. 


nisToiiY  OP  American  Prpj-Sii-urian  Geolooy,  Concluded. 

'I'lu'Tiiiurcntiiin  soriesin  Canada;  its  two  divisions,  as  recognized  in  184.'),  148. 
Conuloiiicrato  iii(rlii<l(;d  in  l.unrcntian  limestones,  148.  Logan  on  tho  strati- 
grajiliy  of  tljo  TjanrtMilian,  lHr);j-57,  140.  Discovery  of  lal^radorito  or  hypors- 
tliono-roci<s  in  'rorrolionnoCounty,  140.  Lithological  description  of  tliom,  l')0. 
Hiinilar  rocks  in  Ijcinstcr  and  Montniorcnci  Counties,  ]'>l.  Tlicir  associated 
gneisses  and  limestones,  l.VJ.  Mincfralugical  composition  of  these  labradorite- 
rocks,  l.");5.    Tlie  constitution  of  plagioiilaso  feldspars,  158. 

'Die  Geology  of  Canada,  publislied  in  IStJS;  tho  accompanying  Athw,  1")4. 
Logan  on  the  succi'ssion  ni  Laurentian  rocks  on  ti>o  Ottawa;  tho  Grenville 
gntMssic  series,  and  tho  Ottawa  gneiss,  l.jo.  Mineralogical  constitution  of  tlieso 
ortlioclase-gncis.ses,  lijo.  Thogneissoid  anortholite  or  labradorite-rocks;  their 
UTiconformablo  superposition  to  tlio  <!renv'.lhi  series,  I5G,  Tliey  aro  distin- 
guished as  Upper  Laurentian  or  Labrailorian,  1.j7.  The  labratlorites  of  ttie 
lower  St.  Lawrence  and  of  Labradf)r,  1.18.  Stratigraphical  discordance  between 
them  and  the  Tjaur(Mitian  at  the  Bay  of  Seven  Islands,  1")9.  Tlie  liaureiitian 
comiiarcd,  in  IS.")!,  with  tlie  ancient  gneisses  of  Europe,  lo9.  The  lal)radorites 
of  Skyo;  views  of  Ma<!ulloch,  Giekio  ami  Ilaughton,  IGO.  Labradoritcs  or 
norites  of  Norway  and  of  Russia,  ItU.  The  Labradorian  named,  in  1871,  tho 
Norian  S(>ries,  Kil.  Titani<i  iron-ores  of  the  Norian,  1()2.  Tho  lal)radoritesof 
Wyoming,  KU.  Tho  Norian  of  Essex  County,  New  York,  1(52.  .James  Hall 
on  its  unconformable  superposition  to  tho  Laurentian,  KiS.  Leeds  on  the 
Norian  rocks  of  this  region,  1(>3.  Ilis  chemical  and  lithological  studies  of 
them,  and  their  ini-hided  orthoclasc-gneiss.  It!!. 

Interstralilied  limc.'stones  of  tho  Laurentian,  lO.J.  Their  eruptive  origin 
maintained  by  some  geologists,  Ki.").  Concretionary  limestone-veins,  or  en- 
doginious  niiusses,  hi,").  Tho  Tiaurentiau  zinc-ores  of  Now  .Jersey,  It;,'),  Miner- 
alogy of  the  Laurentian  lini'-stones,  KJG.  Masses  of  gneiss  included  in  <'alca- 
reous  veins;  examples  at  Port  Henry,  New  York,  KiO.  .Tames  Hall  on  similar 
])henoi'iena,  1(!7.  Lime.stone-veins  in  tho  Norian,  107.  Pro-Cambrian  ago  of 
tlu>se  calcareous  veinstones,  107. 

Organic  remains  of  tlie  Laurentian  period;  the  finding  of  Eozoon  Cana- 
donse,  108.  Its  discovery  anticipated,  108.  Tho  observations  of  McMnllcn  in 
1858  ;  the  Eozoonof  North  IJurgess,  108.  Eozoon  first  described  Ijy  .J.  W.  Daw- 
son in  18<)4, 108. 

Younger  crystalline  rocks  in  H:istings  County,  Ontario,  109.  Observations 
of  Murray,  in  1802,  and  of  Maclarlane,  in  1S()4,  170.  The  conglomerates,  argil- 
lites,  and  limestones  and  the  cldoritic  slates  and  greenstones,  170.  Logan  <ni 
tho  Hastings  lime.stone-series  ill  180(i,  171.  It  is  found  to  <!ontain  Eozoon,  171, 
Venuor's  observations  in  18()0-()9,  171.  Tho  Hastings  series  is  overlaid  by 
Trenton  limestone,  and  rests  nnconformably  on  Iluronian  and  Tiaurentian, 
172.  A  Mica-schist,  and  gneiss  series  in  this  region,  173.  The  succesdon  of 
Tiaurentian  rocks  observetl  by  Vennor,  174.  Pyroxonii;  rocks  with  apatite, 
17r).  The  Ottawa  gneiss  supposed  to  bo  unconformable  with  the  Orenville 
series,  170.  Limestones  of  the  former,  their  economic  minerals,  170.  The 
IJojian  and  Hercynian  gneisses  of  Bavaria,  170.  Daw.son  on  I'^ozoon  and 
annelid-burrows  in  the  Ha.stings  llmestone-.serie.s,  177.    The  rocks  of  Hastings 


CONTENTS. 


K.  xix 


County  Compared  with  those  of  Luko  Superior  ami  tho  Atlaiitio  bolt,  17S. 
The  IListings  limostone-sories  compared  with  tlio  Lower  Taconic,  17s.  Lower 
Taconic  rooks  in  Muiiio,  179.  Tho  similar  rocks  of  St.  John,  New  Brunswick, 
179.  Tho  pro]>(psoil  Terrunovan  series;  it  included  two  terrancs,  ISI.  Tho 
White  Mountain  ^;neissosand  mica-schists,  cjillod  Montallian  in  1S71,  ISl. 

The  Green-Mountain  and  White-Mountain  rocks  helicved  to  bo  altered 
paleozoic  strata,  IHii.  Tho  latter  supposed  to  ho  altered  lluilson-Iliver  yroup, 
or  TJpi>er  Taconic,  ISJ.  TiOj^an  on  their  stratigraplii<!al  arrauf^emcnt  in  three 
syn('linals  in  eastern  Canada,  is:i.  Tiie  magnesianand  mi'iallii'orons  helts,  1S;J. 
Determination  of  the  pre-<''aml)rian  ago  of  these  crystalline  rocks,  1S4.  Peb- 
bles of  tlietn  found  in  Cambrian  conglomerates,  185.  Eaton  and  r'nunonsaa 
to  their  Prnnary  age,  IS.').  Tliey  are  compared  l>y  Macfarlane  and  by  Bigsby 
with  the  Primitive  schisls  of  Norway,  IHC.  Tiie  similar  viowsof  II.  D.  Rogers, 
as  opposed  to  those  of  Logan,  187.  Tho  orystallino  rf>cks  of  Caernarvonshire 
and  Anglcsea;  ditlcring  views  of  Hritish  geologists,  IS7.  'JMitMr  lluroiiian 
age;  Dimelian  and  P(!liidian,  ISS.  Matthews  on  lluronian  in  New  Itruns- 
wiok,  188.  Ilis  I}loomsl)ury  group  not  altered  Devonian,  but  lluronian,  189. 
The  author,  in  1S7(),  on  tho  lluronian  of  the  Atlantic  coast,  ISO.  Its  two  litho- 
logic^d divisions:  pelrosihix-porphyriesof  Massjichusotts,  ISO.  ( Jhloriiic green- 
stones and  8eri)entines,  190.  Intrusive  granites,  191.  Micaceous  quartzites  <il 
Marbleliead,  191. 

Further  description  of  the  petrosilex-rocks,  with  analyses,  lOii.  Their  dis- 
covery in  tho  Blue  Kidge,  in  s<juthern  Pennsylvania,  193.  Compared  with 
the  hiilletlinta  of  Sweden,  lOIJ.  Similar  rocks  in  Missouri,  104.  Pumi)elly 
on  their  nature  and  origin,  104.  lluronian  rocks  in  northciustern  Canada,  and 
Newfoundland,  19,").  Tho  latter  regarded  by  Murray  as  partly  eruptive,  19(>. 
His  view  compared  with  that  of  Logan,  and  both  rejected,  197.  Tho  pro- 
Cambrian  age  of  these  rocks  allirmed  ;  lato  results  of  tho  Canada  survey,  198. 

Unpublished  letter  of  W.  15.  Rogers  on  the  Blue  Ridge  in  Virginia,  108. 
Fontaine  on  tho  siuno  region;  its  Laurentian,  lluronian,  Montalban  and 
Taconic  rocks,  100.  Tho  author  on  Laurentian,  lluronian  and  Montalban  on 
the  Schuylkill,  iti  Pennsylvania,  liUO.  On  tho  I^i'  \er  Taconic,  or  Primal  and 
Auroral  rocks  of  that  region,  liOl.  Their  crystalline  cjharactor,  antl  included 
iron-ores,  201.  Their  partial  resemblance  to  lluronian,  20'J.  C.  U.  Shepard 
(m  the  limonites  of  westtn-n  Connecticut,  20li.  Epigenio  origin  of  c(M-tain 
linionites,  203.    Magnetites  and  limonites  of  tho  Primal  or  Lower  Taconic, 

204.  Crystalline  minerals  of  this  series;  new  species  called  vcnerite,  205; 
The  author  on  s;)-called  talcose  or  nacreous  schists,  20.").  Emmons  on  the 
pyrophyllito  rocks  of  tho  Lower  Taconic,  20o,  Organic  forms  in  this  series; 
Scolithus,  Lingula,  etc.,  20(J.  The  name  of  Taconian  propcsed  lor  the  Lowir 
Taconic,  207. 

Geology  of  the  Blue  Ridge;  Laurentian  of  Roan  Mountain,  North  Caro- 
lina, 207.  The  Montalban  series,  with  granitic  veins,  and  included  diniiteor 
olivine-rcjck,  207.    Taconian  at  theea.stern  base  of  tho  Bhio  Ridge;  it;i(v>lumito, 

205.  Kerr  on  tho  geology  of  North  Carolina;  his  Upper  Laurentian  is  Mon- 
talban, 20S.  His  lluronian  includes  the  Taconian;  charactorsand  distrilmtion 
of  tho  latter  in  N.  Carolina,  208.  Bradley  on  tho  paleo7X)ic  age  of  tlio  rocks  of 
the  Blue  Ri<lge;  reasons  for  rejecting  this  view,  209.  Tho  pre-Cambrian  ter- 
ranes  compared;  their  chemical  and  mineralogical  dilforences,  210.  Relations 
of  Taconian  to  paleozoic  time,  211.  Examples  of  laults  and  inversions  of 
strata,  212.  Tho  hypothesisof  metainorphism,212.  Imitative  forms,  supj)osed 
to  1)0  organic,  212.     Examples  by  J.  B.  Dainx,  from  Vermont,  213.     Discrinii- 


XX  E. 


CONTENTS. 


t 


nation  botwccn  older  iukI  newer  contifrwiis  strata,  214.  Prime  on  Auroral 
and  Trenton  limestones  in  the  Appalaeliian  viilU-y,  in  Pennsylvania,  214.  Tlie 
author  on  another  pro-Silurian  serit>s  therein,  2l.j.  Strati^;rapiiio;il  relati<jns 
of  the  prc-Silurian  terranes,  'JI.'>.  l'"urlii<'r  evidenees  of  a  break  at  the  l)aso  of 
the  Siluro-Ciunbrian,  21(;.  Murray  on  tlie  lluronian  in  Nuwibundland,  217. 
The  great  pro-Cami)rian  erosion  in  that  region,  217.  lluronian  north  of  the 
river  St.  Lawrenee,  217.  Brooks  on  a  supposed  newer  series  in  northern 
New  York,  218. 

Geology  of  Lake  Superior  ;  the  lluronian  distinguished  from  the  Cojjper- 
bearing  series,  210.  TiOgan,  iu  istio,  refers  tiio  latter  t'>  the*  Quebeo  group,  210. 
Views  of  various  writers  on  unstratilied  and  igneous  roelis,  220.  The  author 
on  the  indigenous  eharucter  of  the  lluronian  greenstones,  221.  The  terms  ex- 
otic and  end();icn<)nsa|)plied  to  roirk-nuussos,  221.  Kimball  on  Laurontian  and 
lluronian  of  nortiiern  Mioiiigan,  221.  Credner  on  the  g(M)l()gy  of  the  sjimu 
region,  222.  Its  examination  liy  Brooks  and  Pumiiellj',  222.  UnpuliUshed 
letter  of  the  author  on  tin  o(;ks  of  northern  Michigan.  22:5.  The  newer  erj-s- 
tallino  or  Montall)an  roeksof  the  region,  224.  Subsequent  studies  of  tliem 
by  Brooks,  22r>.  The  lluronian  grt'eustones;  tlieir  lithologieal  tiharaeters  and 
associations,  22(i.  lluronian  greenstones  near  New  Haven,  Conn.,  oalled,  by 
J.  D.  Dana,  tui^tadolerito  and  metadial)ase,  227.  The  province  of  lithology,  and 
its  relations  to  geognosy,  227.  Hawes  on  tlie  dioriiic  character  of  tiicse  green- 
stones, 228.    Serpentines,  and  carbonaceous  rocks  of  the  lluronian,  22H. 

The  Copper-bearing  nxiks  of  Lake  Su[)erior ;  their  supi)osed  stratigrapliical 
relations  to  *  lie  lluronian,  220.  The  question  of  t!i<^  petrosilex-poriihyries, 
229.  Probable  lluronian  age  of  the  Boliemian  mountains,  2110.  Stratigraplii- 
cal break  between  the  lluronian  and  the  Coi>per-bearing series,  230.  The  latter 
distinguished,  in  1S7:5,  as  the  Kewenaw  group,  afterward  <;alled  Keweenian, 
2iil,  Tills  conclusion  ado[)tod  by  Brooks  in  1^7"),  21!  1.  Irving  on  the  geology 
of  Wisconsin,  231.  Laurontian  and  lluronian  of  the  region,  232.  The  so-ciiUod 
altered  Potsdam,  called  lluronian  by  Hall  and  by  Irving,  232.  Its  quartzites 
and  petrosilex-porphyries,  232. 

The  Keweenian  in  Wisconsin,  232.  Sweet  on  its  pre-Cambrian  age,  and  on 
the  overlying  stuidstones,  233.  The  Lake  Superior  or  St.  Mary's  sandstone 
referred  to  the  Potsdam  Ijy  llominger,  233.  Overlying  Calcil'orous  and  Chazy 
formations,  234.  Bradley's  geologictd  map,  1S7<') ;  ho  calls  the  lluronian  altered 
Silurian,  234.  Views  of  Sir  W.  E.  Logan, and  of  Solwyn,  235.  Irving  (m  the 
pre-Cambrian  ago  of  both  lluronian  and  Keweenian,  235.  No  motamorphism 
of  paleoaiic  strata  in  the  west,  23(5.  Relations  of  Taconian  to  Keweenian,  23(5. 
The  arguments  for  the  meso2a)io  ago  of  tho  latter,  237.  Chronological  value  of 
the  niineralogicjd  characters  of  exotic  rocks  considered,  237.  Supjioscil  organic 
markings  in  Keweenian  rocks,  237.  The  two  groups  of  sedimentary  i-ocks  on 
Thunder  Bay,  Lake  Superior,  238.  The  lower  or  carbonaceous  group,  with  sil- 
ver-bearing veins,  238.  The  upper  or  variegated  dolomitic  group,  230.  These 
probably  distinct  from  and  younger  than  the  Keweenian,  antl  called  Animikio 
and  Nipigon  groups,  240.  Views  of  Logan,  Mucfarlane,  Bell,  and  the  author 
as  to  these  rocks,  241. 

List  of  pro-Silurian  terranea  in  North  America,  241.  Local  variations  in 
Cambrian  sediments,  and  their  cause,  242.  Rclationsof  pre-Cambrian  terranea 
to  one  another,  242.  Laurontian  of  the  Rocky  Mountains  and  the  Wahsjitch 
range,  243.  lluronian  of  the  Sierras,  and  uriferous  rocks  of  California,  244. 
Laurontian  and  lluronian  in  tho  Alps;  the  pietri  vcrdi,  244.  Succeeding 
limestone  group  in  that  region,  246. 


\ 


COxVTENTS. 


E.  XX i 


Note  ..„  tho  Mnntanmnvoinst.Mios    '4,1      r  „    .     . 
the  younKer  K,„.Usio  „r  Montall.an  'sJr  1 .     r  I  "'^nervations  of  Bnx.ks  on 

slun. ;  us  estimated  tl.i,.k„.as,  -'is     Tin  r,  i...  '^'"""'^''^"'  *'»  ^'«w  llan.p- 

nradloy  on  the  151..,.   liUhn   in  r  •  ""''  ^'•""""o.s,  L'48.  ' 

^>tsUan..Q..e.,e.,a„.CM;;;!c;,:     ;;;;:;;;  ^^i    ^;.;;;so-.a,U...aU. 

Georgia,-.'.^,).    Tl.o  rooks  of  Atlanf,  -\:-  "'■"^"'"^  "l«frvati„„s  i„ 

Gap,  2.50.    Mont.dl,an  a..>    ^     '    i:;      ?'"'""'"•"'" '^^"""t  Airv  to  r„ak. 
Stone  Mountain.  ,.,,     I>;.  './^.^^^r;, ^"-     ''--....aMo  Ta,.o„ia„   ,..,t.  Si 
and  n.ica-sohists.  -,,.    Tl.e  (' Ih  it      "'«.;•''«"•"  =  N..-  hornM.,,,,,-,^,,,  .j,,,,^ 

251.  Their  supposed  a.tl^^aJir^r  ';■;' :;;;r^'T'''"™"  ^^^'"^ '"  '^-^«!'' 

ron.  s,.ooession.  and  its  (aliacies.  ^^2     ^  i   ^    1^      ''^^  '"•     ''^"^'  '"•-" "^ 

the  MontalLan,   2,-.i'.    Tl.e  arLMn„.nr  .l^Z         '""''''^  ^.ows  ,us  to  the  ago  of 
genesis  of  orystalline  rooks  "v"  ««PIK.sed  tnmsitions,  253.    The 


( 

V 

d 
a 
n 
li 

ol 

a 

t'u 


th. 

OIK 

cru 


CIIArTEU  I. 

IXTRODUCirOX. 
S  1.   In   till)  month  of  Ano-ii.t    isr.:    T 

ConimiasioMcra  for  tlio  <iJl   i!.        '     ""^  ^quested  hy  tlio 

-i'l.  os„oeia,  rcfcro  c rt    ho      °  °"'""  "••"■'  "^  "'»'  «'"'<=. 
director  of  tho  Survey  ",,'^  ''■"'?""="^  °''  ^'■°'-  I'^^'ey,  the 

''"■•<]-.(•  Dr.  (ioTl",d  Prof  p     .f  t  '™'  "'^'='"'>-  '"  "'« 
«-.t«  evi,lo„t  that  tho     ork-  1  ,  "J  ^''''""■'  ■^''"-  ^°  """  i* 

Of  .ho,-r  goognostic':  r:,rtt,r":,t°  ^t  ^v- ""'"^  "  T'^- 

a -.  wi„o  .n,o  Of  i.,.,,,  h.oif;";,::  ;.;;::c;t::;: 

tl.oy  oxotio  lET  "™"'  ""^'S""""^'  ""d  I'ow  far  aro 

onfartrerho?:ft:;T:i;:o'r°'^^'r°"'"'"'--'>" 

Inasmuch  as  thoro  nro  n  Mo'  ?"■  '^"'='»«i°S  ^fata  ? 

«™p-o.c.,.h.;=::fi--t^-;.o.a 

[1  E.J 


2  E. 


SPECIAL    KEI'OUT.      T.  STEKRY  HUNT,  18 V5. 


itiaHmucli,  moreover,  as  other  rocks,  by  many  regarded  as  erup- 
tive, are  found  enclosed  in  the  older  formations,  (the  mineral 
characters  of  which  tliey  are  generally  .supposed  to  ha. c  modi- 
fied,) it  became  evident  that  a  proper  discussion  of  the  trappian 
rocks  would  require  a  review  of  the  geology  of  the  whole  re- 
gion. Add  to  this  the  history  of  the  iron  ores,  some  of  which 
are  commonly  believed  to  have  intimate  relations  witli  the 
trajis  ;  and,  moreover,  the  history  of  the  so-called  azoic  i-oeks, 
and  the  field  presented  for  my  geological  investigations  be- 
comes a  very  wide  one. 

By  Azoic  rocks  are  generally  understood  the  whole  of  the 
Prnnary  crystalline  rocks  of  prepaleozoie  age,  for  which  the 
names  of  Archaean  and  Eozoic  liave  also  been  suggested.  Rog- 
ers, it  is  true,  restricted  the  name  of  Azoic  to  a  portion  of  these 
Primary  rocks,  while  he  designated  another  }iortion  of  them  as 
llypozoic.  I  have,  however,  interpreted  the  term,  as  used  above 
by  Prof.  Lesley,  in  its  usual  sense,  and  .shall  include  under  this 
title  the  whole  of  the  Primary  or  Eozoic  formations  known  in 
Pemis^'lvania. 

§  2.  The  region  to  which  my  inquiries  were  directed  is  that 
part  of  the  State  lying  to  the  south  and  east  of  the  North  or 
Kittatinny  Mountain,  and  includes,  besides  the  Mesozoic  sand- 
stones and  the  rocks  designated  by  Prof.  Henry  D.  liogers  as 
the  Primal,  Auroi-al  and  Matinal  divisions  of  the  Paleozoic 
Bystem,  a  great  development  of  crystalline  stratitied  rocks. 
These  were  by  him  divided  into  an  older  Uneissic  or  llyijozoic 
series,  and  an  upper  Semi-metamorphic  or  Azoic  series,  the  re- 
lations of  which  to  one  another  and  to  the  I'aleozoic  system 
are  very  intimate,  and  gave  rise  to  certain  ambiguities  in  the 
descriptions  and  the  nomenclature  as  set  forth  by  liim  in  his 
filial  report  on  the  geology  of  I'ennsylvania,  published  in  lWo8. 

§  ;}.  As  regards  the  distinctions  between  the  liypozi/ic  and 
Azoic  series,  those  were  declareil  to  be  :  "■  First,  an  obvious  and 
very  general  dillerence  in  the  composition  of  the  two  sets  of 
strata:  secondly,  a  marked  dillerence  in  their  conditions  of 
metamoiphism :  and  thirdly,  and  more  esjiecially,  u  striking 
contrast  in  the  direction  and  manner  of  their  u}ilift ;  the  [ili- 
cations  and  utidulations  of  the  less  metaniorphic  series  dipping 
almost  invariably  south-eastward,  while  the  gneiss,  in  many 


IIYPOZOIC    AND    AZOIC    ROCKS    OF    ROGERS. 


E  :i 


localities,  has  no  symmetrical  foldings,  but  only  u  broad  out 
crop,  dipping  to  a  different  quarter.  These  structural  dissimi- 
larities imjily  essential  differences  in  the  direction  and  date  of 
the  crust-movetuents  which  lifted  and  transforn.ed  the  respec 
tive  grou])s,  and  led  the  geologists  of  I'ennsylvania  and  Vir- 
ginia to  a  conviction  that,  over  at  least  many  tracts,  there  would 
yet  be  discovered  a  physical  unconformity  lioth  in  strike  and 
dip.  It  was  not,  however,  until  a  relatively  late  date  in  the 
prosecution  of  the  Geological  Survey  of  Pennsylvania  that  the 
geologist  of  that  State  detected  positive  evidence  of  this  [»hysi- 
cal  break,  ami  of  a  lapse  of  time  between  the  two  groups  of 
Btrata." 

§  4.  "  We  have  then  in  the  Atlantic  slope,  by  actual  demon- 
stration, but  one  physical  break  or  horizon  of  unconformity 
throughout  the  immense  succession  of  altered  crystalline  sedi- 
mentary strata  and,  within  this  region,  but  one  paleontological 
horizon — that,  namely,  of  the  already  discovered  dawn  of  life 
among  the  American  strata.  This  latter  plane  or  limit,  mark- 
ing the  transition  irom  the  nou-fossiliferous  or  Azoic  deposits 
to  those  containing  organic  remains,  lies  within  the  middle  of 
the  Primal  series  or  group  of  the  I'ennsylvania  survey  ;  that  is 
to  say,  in  the  Primal  white  sandstone,  which,  even  where  very 
vitreous,  and  abounding  in  crystalline  mineral  aggregations, 
contains  its  distinctive  fossil,  the  SeolUhus  linearis.  The  I'rimal 
slates,  beneath  the  sandstone  and  in  intimate  alternation  with 
it,  possess  not  a  vestige  of  organic  life,  nor  has  any  such  yet 
been  discovered  anywhere  within  the  limits  of  the  Atlantic 
slo])C,  or  on  the  northern  or  western  borders  of  the  great  Ap- 
palachian basin  of  ^orth  Ainerica,  either  in  the  Lower  Primal 
slate  or  in  the  other  Semi-metumorphic  grits  and  schists  physi- 
cally conformable  with  it,  into  which  the  true  Paleozoic  se- 
quence of  our  formations,  physically,  extends  downwards." 

§5.  We  have',  then  in  the  language  of  Rogers.  "  two  main 
horizons,  sub-dividing  the  more  or  less  nictamorphic  strata  of 
the  Atlantic  slope  in  three  systems  or  groups  ;  the  one,  a  physi- 
cal break  or  interruption  in  the  original  dejiosition  of  the 
masses ;  the  other,  a  life-limit  or  plane,  denoting  the  first  advent, 
so  far  as  yet  discovered,  of  oiganic  l)eings.  As  tliese  two  planes 
are  not  eoincitlent,  Init  include  between  them  a  thick  group  of 


M 


m 


4  E. 


SrEClAL    UEl'OKT    OF    T.    STEIUIY    ULNT,    1875. 


Bedimeiitary  rocks  separated  from  the  lower,  physically,  and 
from  the  ujtper,  ontologically,"  the  author  was  led  "  to  employ 
a  classitication  which  recoo;nizc3  a  three-fold  division  of  all 
these  lower  strata."  These  three  groups  he  defined  to  be  the 
ILjpozok  rocks,  or  those  beneath  any  life-bearing  strata;  the 
Azoic^  or  those  destitute  of  any  discovered  relics  of  life  ;  and  the 
Paleozoic,  containing  the  remains  of  ancient  life.  (Sec  the  Ge- 
ology of  Pennsylvania,  1858,  vol.  I,  pages  62-64.) 

§  6.  In  addition  to  the  relation  of  continuity  already  asserted 
between  the  Azoic  and  Talcozoic  groujis,  we  arc  liirther  told, 
in  the  chapter  just  quoted,  that  the  "Azoic  or  talco-niicaceous 
group  is  a  genuine  downward  extension  of  the  I'rinuil  i'aleo- 
zoic  scries;"  while  in  a  succeeding  chapter,  tiie  whole  of  the 
Azoic  series  is  expressly  included  in  the  I'aleozoic  system,  of 
which  it  constitutes  the  lower  portions,  in  the  preceding  ex- 
tracts, the  Azoic  rocks  are  sx)oken  of  as  comprising  the  Lower 
I'rimal  slate,  and  a  group  of  tSemi-metaniorpliic  grits  and 
schists  physically  conformable  with  il;  but,  farther  on  in  the 
pages  of  Kogers,  the  latter  alone  are  distinguished  by  the  name 
of  Azoic,  under  the  head  of  the  Paleozoic  system. 

§  7.  The  Ajjpalachian  Paleozoic  strata  of  Pennsylvania,  as 

defined  by  our  author,  arc  said  to  be,  in  asccndiug  order,  as 
follows: 

"  Primal  Crystalline  Schists  (or  Azoic  Group.) — A  very 
thick  and  widely  difiused  group  of  semi-crystalline  strata,  in- 
durated clay -slates,  talcose,  micaceous  and  hornblendic  schists 
and  gray  silicious  grits,  without  visible  fossils,  but  in  closo 
physical  relations  with  tlie  overlying  fossiliferous  l*rimal  rocks, 
and  apparently  a  portion  of  the  Paleozoic  system." 

To  this  division  succeeds  four  mjmbcrs,  described  as  portions 
of  the  Primal  Series,  namely  : 

"  Prlmal  Conqlomkrate. — A  heterogeneous  conglomerate 
composed  of  quartzose,  feldspatl.'ic  and  other  pebbles,  included 
in  a  silicious  or  talco-silicious  cement.  This  rock  does  not  ap- 
pear in  Pennsylvania,  but  is  largely  developed  in  Virginia  and 
in  Tennessee,  where  it  has  a  thickness  of  150  feet.  This  for- 
mation, jind  the  preceding,  seem  to  lie  below  the  lowest  ascer- 
tained fossiliferous  horizon." 


PALEOZ'UC    KOCKS   OF    HOGEllS. 


i:.  5 


"Primal  Older  Slate. — A  sandy  slate  of  al)rown  or  green- 
ish gray  color,  containing  much  lelJspatliic  and  talcose  matter. 
It  has  hitherto  disclosed  no  fossils.  The  thickness  of  this 
rock  has  not  been  ascertained  in  Pennsylvania,  the  beds  being 
too  much  folded.     In  Virginia  it  is  1,200  feet  thick." 

"  1'rlmal  White  Sandstone. — A  compact,  fine-grained  white 
and  yellowish  vitreous  sandstone,  containing  specks  of  kaolin. 
The  stratum  is  distinguished  by  a  cylindrical  stem-like  fossil, 
the  Scolilhus  lincuris,  which  crosses  the  beds  in  a  perpendicular 
direction.     l*robable  thickness  about  300  feet." 

"  Prlmal  UrrER  Slate. — A  greenish  blue  and  brownish  talco- 
argillaceous  slate,  very  soft  and  slialy  ;  its  only  fossil  a  peculiar 
fucoid.     It  is  probably  about  700  feet  in  Pennsylvania." 

§  h.  To  these  succeed  the  Auroral  Series,  consisting  of  two 
members,  which  are,  in  ascending  order: 

''Auroral  Calcareous  Sandstone. — A  coarse  gray  calca- 
reous sandstone,  containing  drusy  cavities  enclosing  crystals  of 
quartz  and  calcareous  sjia..  Within  the  limits  of  Pennsylvania 
this  occurs  chietly  in  Northampton,  Centre  and  Huntingdon 
counties.     It  is  about  sixty  feet  at  l^aston." 

"Auroral  Maqnesian  Limestone. — A  light  blue  and  bluish- 
gray  massive  limestone,  containing  generally  from  ten  to  thirty- 
five  per  cent  of  carbonate  of  magnesia.  In  the  southwestern 
part  of  Pennsylvania  it  contains  thick  beds  of  chert.  Its  thick- 
ness is  from  2,500  to  5,500  feet." 

§  9.  Of  these  divisions  the  Primal  white  sandstone  was  by 
llt)gers  regarded  as  the  equivalent  of  the  Potsdam  of  the  New 
York  series  ;  and  the  lower  and  upper  members  of  the  Auroral, 
respectively,  as  the  representatives  of  the  Caleifbrous  sandiock, 
and  the  united  Chazy  and  Black  Kiver  limestones  of  New 
York. 

The  Auroral  is  followed  in  ascending  order  by  the  Matinal 
Scries,  in  three  divisions,  namely:  the  ilatinal  argillaceous 
limestone,  tlio  Matinal  black  slate,  and  the  Matinal  shale; 
supposed  to  be  equivalents  respectively  of  the  Trenton  lime- 
stone, the  Utica  slate,  and  the  so-called  Hudson  Kiver  shales 
of  New  York.     (Ibid,  I,  page  104.) 

§  10.  Crystalline  characters  were  not,  however,  according  to 
Rogers,  supposed  to  be  contined  to  the  liypozoic  and  the  Azoic 


?j 


6  E. 


SPECIAL    IJEPORT.      T.  STEllKY    HUNT,  187J. 


H  '   hV"! 


or  Lower  Priraal  strata.  The  Primal  white  sandstone  and  the 
Upper  Primal  slates,  as  well  as  the  Auroral  and  Matinal  series, 
in  various  localities,  are  described  as  being  more  or  less  crystal- 
line in  form,  from  so-called  metamoridiic  action  ;  which  is  even 
supjiosed  by  Rogers  to  have  changed  the  Mesozoic,  in  some 
places,  into  a  crystalline  rock.  Tiie  whole  of  the  Primal  strata 
below  the  white  sandstone  are  elsewhere  described  as  alterna- 
tions of  talcoid  silicious  slate,  talco-micaceous  slate  and  quartz- 
ose  micaceous  rock,  usually  schistose,  besides  other  strata  wiiieh 
are  nearly  pure  clay-slate.  Greenish  talcose  slates  arc,  more- 
over, said  to  be  associated  both  with  the  white  massive  lime- 
stone and  the  blue  limestone  of  the  Auroral  series. 

§  11.  The  larger  part  of  the  crystalline  rocks  of  the  State  are 
by  Rogers  referred  to  theGneissicor  llypozoic  series,  although 
we  are  told  that  near  the  Susquehanna  it  is  difficult  to  distin- 
guish the  silicious  talco-mieaceous  I'rimal  from  the  more  mica- 
ceous beds  of  the  llNpozoic.  Elsewhere  it  is  declared  that 
whore  these  Lower  Primal  or  Azoic  strata  "  display  their  maxi- 
mum amount  of  crystalline  structure  or  metamorphism,  the 
members  of  the  twogroujis  often  simulate  each  other  so  closely, 
and  indeed  are  so  identical  in  mineral  aspect  and  structure,  as 
to  bailie  all  attemptsat  distinguishing  them  lithologically  ;  nev- 
ertheless it  will  appear  IVom  the  evidence  embodied  in  the  sec- 
tions illustrating  this  country  that  they  are  distinct  systems, 
occuiiying  separate  zones,  susceptible  of  delineation  in  the  geo- 
logical map."     (Ibid.  I,  page  60.) 

§  12.  He  defined  three  areas  or  districts  of  the  Gneissic  or 
llypozoic  series  in  tlie  State  of  J'cnnsylvania.  The  Northern 
district,  being  the  South  Mountain  belt,  is  a  prolongation  of  the 
Highlands  of  the  Hudson  and  of  New  Jersey,  whicli  crossing 
the  Delaware  below  Easton,  extends  to  Reading  on  the  Schuyl- 
kill, stretching  along  the  north  side  of  the  Mesozoic  sandstone 
belt.  The  Middle  gneissic  district  extends  from  near  Valley 
Forge  on  the  Schuylkill,  westward  into  J^ancastcr  county,  and 
includes  the  Welsh  Mountain,  between  the  Mesozoic  on  the 
north  and  the  limestone  valley  of  Chef  ter  county  on  the  south. 
The  third  or  Southern  district  is  that  extending  from  the  Dela- 
ware at  Trenton  to  the  Susquehanna  south  of  the  State  line, 
and  lies  whoUv  south  of  the  limestone   vallev  of  Chester  and 


CJNEISSIC    DISTRICTS    OF    ROGIiUS. 


E.  7 


Montgomery  counties,  except  when  the  gneiss  passes  around  the 
east  end  of  the  limestone,  and  lies  between  it  and  the  southern 
border  of  the  Mesozoic  for  a  little  distance  near  the  eastern 
corner  of  the  last  named  county.  This  SouiIktu  gneissic  dis- 
trict, in  the  words  of  liogcrs,  '"lireaks  otf  to  the  west  of  the 
Brandywine  river  in  a  succession  of  narrow  tongues.  Near  the 
State  line  of  Delaware  it  sends  forth,  however,  through  the 
south-east  corner  of  Chester  county,  a  continuous  and  widening 
belt  to  the  Susquehanna."  To  the  "west  of  the  Brandywine 
the  gneissic  rocks  sink  under  the  altered  I'rimal  strata  in  a 
succession  of  anticlinal  lingers  on  slender  j)romontorics."  The 
line  of  demarkation  between  these  two  "series  is  nut,  however, 
a  simple  une,  but  is  intricately  loo})ed  in  consequence  of  numer- 
ous nearly  parallel  anticlinal  foldings  of  the  strata,  sending 
promontories  or  tingers  of  the  older  rocks  within  the  area  of 
the  newer  or  Semi-metamorphic  to  the  west  of  their  average 
boundary."     ([bid  I,  i)ages  Go,  GO,  G7.) 

To  the  west  of  this  irregular  boundary,  the  whole  of  the 
crystalline  rocks,  which,  i)n  both  sides  of  the  Susquehanna,  ex- 
tend to  the  south  of  the  limestone  valley  of  Lancaster  cuunty 
as  far  as  the  Maryland  line — where  through  the  narrowing  of 
this  valley  they  are  brought  to  the  Mesozoic — are  rei)resented 
by  Rogers,  both  in  the  rej)ort  and  in  the  geological  map,  as 
"  Primal  altered,"  with  some  areas  o\'  "Auroral  altered." 

§  18.  Still  farther  west,  and  beyond  the  Mesozoic,  is  a  large 
and  important  mountain  area,  the  northern  extension  of  the 
Blue  Ridge,  stretching  nearly  to  the  Susquehanna,  which  is  also 
described  by  Rogers  as  ''Primal  altered"  (Ibid.  1,  {)age  204.) 
This,  liowever,  in  the  geological  maj),  is  designated  as  unaltered 
"Primal."  The  same  is  true  ot  some  stuall  areas  of  crystalline 
slates  which  ap[)ear  iji  the  midst  of  the  Auroral  limestt)ne  near 
theSus([uehanna,  to  the  south-east  of  the  Mesozoic.  In  calling 
attention  to  this  discrepancy  bi'tween  the  maii  and  tin  text,  I 
wish  to  jtoint  to  another  of  eonsideral)le  inqiortance.  It  will 
bo  found,  (at  least  in  the  copy  of  the  geoU)gical  map  of  L*emi- 
sylvania  before  me,)  that  the  Gneissic  series  in  the  tlie  legend 
is  represented  by  a  diagonally-lined  pjjik  color,  which  however, 
on  the  map,  is  confined  tc  the  Southern  district ;  the  Middle  and 
Northern  gnei.ssie  districts  being  of  a   piidc  color,  but   unlinod. 


M 


8  E. 


SPECIAL    KEPOKT.       T.  STERRY    HUNT,  1875. 


Inasmuch  as  Rogers  refers  the  whole  throe  to  the  same  series, 
tliere  is  evidentlj'  an'  error  on  the  part  of  tiie  cartograplier. 
It  seems  prohuble  the  unlined  pink  of  the  districts  hist 
mentioned  was  intended  to  represent  the  gneiss.  The  student 
of  the  map  will  also  bear  in  mind  that  the  areas  designated  as 
"Primal,'  near  York,  and  west  of  the  Mesozoic,  and  colored  a 
pale  yellow,  Avithout  lines,  should,  in  conformity  with  the 
text  of  liogers,  receive  that  color  which,  according  to  the  le- 
gend, belongs  to  the  "Primal  altered."  It  may  also  be  ob- 
served that  the  diagonally-lined  pale  yellow,  said  in  the  legend 
to  represent  Primal  roofing-slates,  does  not  appear  upon  the 
geological  map. 

§  1-1.  The  characters  of  the  three  gnesssic  district  are  de- 
scribed with  some  detail  by  Rogers,  who  shows  that  the  rocks 
of  the  Northern  and  Middle  districts  are  very  unlike  those 
of  the  Southern.  They  consist,  according  to  him,  of  coarse 
gneisses,  resembling  granite,  but  distinctly  stratified,  often 
made  up  chiefly  of  quartz  and  feldspar,  frequently  hornblendic, 
and  abounding  in  magnetic  iron  ore,  but  rarely  containing 
mica.  lie  also  notes  the  rarity  of  micaceous,  talcose  or  chlo- 
ritic  rocks,  which  abound  in  the  Southern  district.  The  Middle 
district  presents  some  small  exposures  of  highly  crystalline 
limestone  with  graphite  ;  and  the  Northern  one,  near  Easton, 
also  exhibits  beds  of  serpentine,  with  some  crystalline  car- 
bonate of  lime,  accompanied  with  tremolite,  light  colored  jiy- 
roxene,  brown  tourmaline,  graphite,  and,  as  I  have  observed, 
with  large  crystals  of  magnesian  mica.  The  mineralogical 
and  lithological  characters  of  these  rocks  are  similar  to  those 
met  with  in  the  Highland  range  in  New  York  and  New  Jer- 
yey,  of  which  this  is  a  continuation;  and  it  was  after  a  careful 
consideration  of  all  these  circumstances  that  the  geological 
survey  of  Canada,  in  the  map  of  eastern  North  America,  pub- 
lished in  18GG,  represented  both  the  Northern  and  the  Middle 
gneics'c  districts  of  Pennsylvania  as  belonging  to  the  Laureu- 
tian  series  ;  to  which  the  gneisses  of  the  Highland  range  and 
the  Adirondacks  had  already  been  referred. 

§  15.  The  geological  structure  of  these  two  gneissic  regions  in 
Pennsylvania  was  described  by  Rogers  as  presenting  a  series  of 
closely  appresscd  folds,  most  clearly  seen  in  the  South  Mountain, 


SOUTHERN    GNEISS    DISTOICT. 


E.  9 


of  which  he  says,  "It  will  be  seen  that  from  one  end  of  tho 
ran^e  to  the  other  the  gneiss,  and  the  older  Appalachian  strata 
in  contact  with  it,  are  bent  into  a  series  of  folded  or  inverted 
llcxuies;  that  is  to  say,  having  the  strata  in  the  north  leg  of  each 
anticlinal  turned  over,   and   dipping  steeply  to  the  south,  or 
^rather  to  the  south-east,  in  accordance  with  the  law  so  univcr- 
salthroughout  our  whole  Appalachian  chain.     Near  the  Dela- 
ware, as  shown  both  in  the  general  and  the  local  sections,  there 
are  three  distinct  ridges  of  the  gneiss,  separated  by  two  syncli- 
nal troughs  of  the  Auroml  limestone.     IJere  the  entire  breadth 
of  the  chain  is  almost  seven  and  a  half  miles.     At  the  eastern 
corner  of  iJcrks  county  the  breadth  is  about  six  miles.     Here 
they   (the   ridges)  consist   almost   exclusively  of  the   gneissic 
rocks.     Near  the  Schuylkill,  the  whole  belt  is  much  contracted, 
consisting  chietly  of  the  spurs  of  the  Neversink  mountains, 
and  the  ridges  are  composed  almost  exclusively  of  the  Trimal 
white  sandstone  in  an  altered  and  much  indurated  state."   (Geol. 
I'enn.  II,  page  94.)     The  above  structure  is  shown  in  numerous 
sections  given  by  Rogers. 

§  IG.  In  further  illustration  of  the  inversion  of  the  strata 
our  author  remarks  that  along  the  southern  side  of  the  great 
limestone  valley,  near  the  Lehigh,  tho  dip  of  the  limestone  is, 
in  very  many  places,  to  the  southward,  or  towards  the  gneissic 
belt,  sometimes  at  an  angle  of  00°.  He  adds:  ''The  existence 
of  a  steep  southern  dip  along  the  south  side  of  this  valley  is  in 
strict  analogy  with  tlie  position  of  the  rocks  generally  in  tho 
valleys  of  the  whole  South  Mountain  chain,  and  implies  an 
overtiming  of  the  strata  to  the  north.  This  folding  of  the  beds 
upon  themselves  in  the  synclinal  axis  of  our  first  great  moun- 
tain, though  highly  curious,  is  a  i)revailing  feature  from  Ver- 
mont to  Tennessee."     (5th  Annual  Keport,  page  25.) 

§  17.  We  have  next  to  consider  the  gneissic  rocks  of  the 
Southern  district,  the  difi'erence  between  which  and  the  North- 
ern one  (setting  aside  for  the  jiresent  that  of  the  iliddle  dis- 
trict, declared  to  be  similar  to  the  Northern)  is  referred  to  by 
Kogers  as  "an  essential  want  of  corresiK)ndence  between  the 
two  regions,  in  tho  gneiss  itself,"  and  as  a  "marked  dilierence  in 
the  composition  of  the  predominant  rock  of  the  two  gneissic 
ranges,  which  must  be  ascribed  to  an  original  ditftirence  in  the 


m 


10  E. 


SPECIAL   KEl'OKT.       T.  STERUY  HUNT,  1875. 


hi 


chemical  nature  of  the  strata.''  This  Southern  district  more- 
over presents  in  its  ditierent  parts  such  dissimilarities  that 
Rogers  was  led  to  divide  it  into  three  longitudinal  belts,  dis- 
tinguished by  mineralogical  and  lithological  characters.  The 
importance  which  I  ascribe  to  these  three  divisions  is  such  that 
I  condense  from  the  pages  of  Prof.  Rogers  the  following  de- 
scriptions (Geol.  Penn.  I,  pages  64-10-4.). 

§  18.  The  southern  division  or  group  ot  the  Southern  gneissic 
district  is  that  which  is  seen  on  the  Schuylkill  from  Gray's 
Ferry  to  tlie  upper  end  of  Manayunk,  and  includes  the  region 
of  Philadelphia  and  Gcrmantown.  Of  its  gneissic  rocks,  the 
most  common  or  typical  variety  of  all  is  a  gray,  bluish,  r..;her 
finely  laminated  mixture  of  quartz,  feldspar  and  mica ;  the 
quartz,  for  the  most  part,  white  or  trans])arent,  the  feldspar 
usually  white,  and  the  mica  generalh-  black  or  dark  brown,  and 
in  small  plates.  This  rock  occasionally  includes  small  garnets. 
Next  in  frequency  to  this  is  a  dark  bluish-gray,  sometimes 
greenish-black  gneiss,  composed  of  hornblende  au(i  quartz, 
sometimes  with  a  little  feldspar;  the  hornblende  always  greatly 
predominating.  This  rock  is  usually  very  iine-grained  and 
thinly  bedded. 

A  third  common  variety  in  this  group  is  a  micaceous  quartz 
rock,  generally  of  a  light  gray  color.  Some  beds,  from  a  pre- 
dominance of  finely  granular  ([uartz,  and  a  subordinate  amount 
of  disseminated  mica,  have  the  characters  of  a  whetstone.  A 
much  coarser  kind  of  gray  micaceous  gneiss,  consisting  of  a 
predominance  of  rather  large  Hakes  of  mica,  with  a  subordinate 
quantity  of  feldspar  and  quartz,  occurs  interstratitied  with  all 
these  other  species,  as  a  very  usual  transition-variety  between 
the  ordinary  gray  gneiss  and  the  highly  micaceous  kinds,  which 
apitroach  mica-slate.  It  is  very  usual  to  find  the  typical  gneiss 
alternating  with  the  hornblendic  species,  and  both  of  these  al- 
ternating with  the  quartzo-micaceous  variety.  Interst ratified 
among  these  varieties  f)f  gneiss  are  beds  more  or  less  thick,  so 
abounding  in  mica  as  to  be  entitled  to  the  name  of  mica-slate. 
Occasional  beds  of  the  typical  feldspathic  gneiss  are  made 
}KM-phyritic  by  the  presence  of  more  or  less  insulated  segrega- 
tions of  crystalline  feldspar,  the  longer  axes  of  which  generally 
lie  jtarallel  to  the  lamination   of  the   rock.     Garnet  in  small 


SOUTIIEKN    (iNKISS    DISTRICT. 


K  11 


isolated  crystals  is  common  in  tiiL-su  rocks,  especially  in  tliu 
more  micaceous  varieties,  besides  staurolite,  cyanite  and  rutiJe. 
§  19.  The  stratified  rocks  of  this  Philadelphia  group,  accord- 
ing to  Kogers,  enclose  various  "unstratitied  or  true  igneous 
rocks"  including  "a  peculiar  feldspathic  sijetiite  (a  somewhat 
hornblendic  granite)  in  thick  dykes,  also  a  white  coarse- 
grained granite,  consisting  of  feldspar  and  (juartz  in  tortuous 
and  sometimes  ramilying  \o'\n'6,  yrcen stone  and  other  forms  of 
trap-rock  in  dykes,  and  also  quartz,  chroniiferous  iron  ore  and 
other  minerals,  occurring  singly  or  associated  in  the  shape 
of  elongated  thin  dykes  or  narrow  veins.  To  these  should  per- 
hai)S  be  added  some  of  the  masses  of  ser}ientine,  for  the  unstrati- 
tied  character  of  these  last  named  is  no  longer  doubtful." 

§  20.  The  middle  division  or  groujt  of  this  Southern  gneissie 
district,  where  it  a[)pears  on  the  t;cliuylkill,  is  described  by  our 
author  as  very  similar  to  the  southern  one,  and  as  consisting  of 
an  alternation  of  four  principal  varieties  of  rock.  The  most 
abundant  is  a  very  micaceous  and  garnetiferous  gneiss,  includ- 
ing feldspar  and  quartz,  and  having  a  waved,  twisted  or  undu- 
lating lamination,  due  to  the  fact  that  tlie  crystalline  plates  ot 
mica,  displaced  by  the  grains  of  quartz,  are  often  arranged  ob- 
liquely to  the  bedding  of  the  rock.  The  next  most  common 
variety  is  described  as  consisting  almost  entirely  of  this  wavy 
mica.  The  rock  however  graduates  into  the  more  micaceous 
sorts  of  gneiss  by  a  greater  or  less  admixture  of  finely  granular 
crystalline  quartz,  feldspar  and  hornbk'nde.  Thesoutliern  halt" 
of  this  middle  group  consists  of  an  alternation  of  these  two  varie- 
ties of  micaceous  gneiss,  with  beds  of  athinlv  laminated  horn- 
blendic  gneiss;  which  may  sometimes  rather  bo  called  a  horn- 
blende-slate. 

§  21.  The  northern  half  ol'  the  group  consists  largely  of  a 
fourth  variety,  described  as  a  gray,  fine-grained  mixture  ot 
granular  quartz  and  minutely  crystalline  scales  of  mica,  the  for- 
mer predominating  and  constituting  a  kind  of  wlu'tstone.  This 
rock  breaks  readily  into  long  narrow  masses,  with  smooth  sides 
and  ragged  extremiti(!S,  like  half-decayed  tibrous  wood.  On 
its  southern  side,  this  rock,  which  occupies  a  considerable 
breadtii,  is  said  to  alternate  with  the  coarse  mica-slates,  and  on 


ilJ 


;;(■ 


12  E. 


SPECIAL  REPORT.       T.  STEURY    HUNT,  1875. 


the  north  with  greenish  talcoso  slates,  which,  with  serpentines 
and  steatite,  mark  the  summit  of  the  middle  group  of  these 
gneiwsic  rocks,  as  defined  hy  Rogers.  This  steatitie  range  is 
descrihed  as  extendiiij;  from  near  Chestnut  Hill  to  about  a  mile 
west  of  Morion  Square,  gradually  widening  from  a  narrow  belt 
on  the  Wissahickon  to  one-eighth  of  a  mile  on  the  iSchuyl- 
kill,  and  to  nearly  four  times  that  breadth  two  miles  farther 
westward  ;  beyond  which  it  is  said  to  divi<le  into  two  branches, 
which  cross  Mill  creek  three-eighths  of  a  mile  asunder,  and  thin 
out  beyond.     (4th  Ann.  Report,  page  17.) 

§  23.  The  third  or  northern  division  of  the  rocks  of  the  South- 
ern gneissic  district  is  described  by  Rogers  as  consisting,  first, 
of  a  massive  feldspathic  gneiss,  often  j)or[ihyritic,  some  of  it 
micaceous,  and  some  resembling  stratified  syenite  ;  and,  secondly, 
of  a  dark  hard  hornblcndic  gneiss,  thinly  laminated  and 
strongly  banded.  It  is  farther  described  as  marked  by  the  pre- 
vailingly massive  character  of  its  bedding,  its  large  excess  of 
feldspar,  and  comparative  deficiency  of  quartz,  hornblende  and 
mica,  which  latter  mineral  is  generally  black  and  in  very  mi- 
nute scales. 

The  gneiss  of  this  northern  division,  near  the  Neshaminy  in 
Bucks  county,  contains  a  small  bed  of  crystalline  limestone, 
accompanied  by  pyroxene,  hornblende,  tabular-spar  and  gra- 
phite;  which  latter  mineral  was  at  one  time  mined  in  the  vi- 
cinity.    (Ibid,  page  14.) 

§  23.  The  most  remarkable  feature  of  this  Southern  gneissic 
district  is,  according  to  Rogers,  the  northern  dip  in  the  strata, 
"which  prevails  all  along  the  Schuylkill,  with  very  few  local 
and  trivial  exceptions,  until  we  approach  the  upper  or  northern 
side  of  the  third  or  northern  belt,  where  the  rocks  arc,  for  the 
first  time,  for  any  considenable  width  of  outcrop,  folded  and 
lifted  into  a  generally  almost  perpendicular  dip."  The  ordinary 
or  average  angle  of  inclination  of  the  strata  in  the  greater  por- 
tion of  the  district  may  be  slated  to  vary  between  30°  and  50°  ; 
the  prevailing  direction  of  dip  being  somewhere  between  N. 
20°  E.  and  N.  80°  E.,  and  the  undulations  and  contortions  rare 
and  insitrnifieaut.  In  some  few  cases  thev  attain,  for  short  dis- 
tances,  dips  ajiproaching  to  the  vertical,  as  at  Fairmount,  where 


SOUTHEKN   GNEISS    DISTRICT. 


K.  13 


i;ra- 

VI- 


or- 


"  the  strata  are  traversed  by  nuniorous  eonspicuous  Joints,  pre- 
senting at  a  little  distance  a  dccoi)tive  appearance  of  a  nearly 
horizontal  stratification,  in  tliickand  almost  parallel  beds.  This 
is  not  to  be  confounded  with  the  genuine  stratilication  or  grain 
of  the  rock,  as  marked  by  the  structural  distribution  of  mica 
and  other  minerals." 

§  24.  This  predominant  northern  dip  is  preserved  across  the 
southern  and  middle  divisions  of  the  Southern  gneissic  district 
until  we  reacb  the  vicinity  of  the  steatite  belt,  where  for  th«  first 
time  the  rocks  "present  a  succession  of  synclinal  and  anticlinal 
undulations."  In  this  division  of  the  section  the  inclination  of 
the  strata,  still  to  a  large  extent  towards  the  north,  is  at  all  an- 
gles from  30°  up  to  70°.  It  is  worthy  of  note  that  the  steatite 
bed  itself  gives  evidence  of  a  synclinal  wave  in  the  dii^,  for  the 
talc-slates  and  mica-slates  to  the  south  of  it,  for  several  hundred 
yards,  dip  steadily  towards  the  north  at  an  angle  of  about  30°, 
while  those  of  the  northern  side  of  the  quarry  show  a  steeper 
inclination  to  the  south.  To  the  north  of  the  steatite  range 
the  northern  dip  is  quickly  resumed,  and  in  this  part  of  the 
mica-slate  belt,  both  on  the  Schuylkill  and  the  Wissahickon, 
the  dip  is  steeply  towards  the  north. 

§  25.  "Entering  now  the  northern  division  of  the  district, 
with  its  hafder  feklspathic  gneiss,  we  encounter  the  most  ir- 
regularly dipping  or  undulating  portion  of  the  whole  gneissic 
zone.  Ajjproaching  the  quarries  of  blue  porphyroidal  gneiss, 
at  the  lower  limit  of  this  tract,  we  meet  with  a  steeply  com- 
pressed anticlinal  axis  in  the  strata,  marked  by  a  strong  dyke 
of  syenitic  granite.  Here  the  south  dips  arc  70°,  while  the 
north  ones  vary  from  45°  to  55°.  Passing  the  quarries,  we  im- 
mediately encounter  a  wide  space  of  more  than  a  fourth  of  a 
mile,  in  which  the  I'ocks  are  almost  horizontal,  and  towards  the 
northern  edge  of  this  we  perceive  an  axis,  or  turn  in  the 
dip,  making  a  broad,  regular  synclinal  or  basin.  From  the 
northern  edge  of  this  trough  to  the  upper  limit  of  the  whole 
gneiss  formation,  the  gneiss 'is  closely  folded  and  compressed 
into  very  steep  or  nearly  perpendicular  dips,  with  numerous 
short  plicatures. 

§20,  "If  now,"  says  Prof.  Rogers,  "we  review  these  inter- 
esting features  in  the  structure  of  this  broad  zone  of  gneiss,  we 


I  m 


14  E. 


SPECIAL    ItKl'OKT.       T.  riTEURY    HUNT,  1875. 


can  liardly  resist  the  conclusion  tliiit  in  the  tlirec  holts  |)aHsod 
over  by  our  section,  there  are  really  hut  two  groups  of  rocks,  a 
lower  and  a  higher,  and  thus  the  entire  zone,  viewed  broadly, 
constitutes  hut  one  synclinal  wave  or  hasin;  the  liarder  telds- 
pathic  and  hornhlcndic  rocks  dijiping  northward  throui^hout 
the  whole  southern  belt  or  outcrop, and  reappearing  in  steep  and 
multiplied  contortions  on  the  other  side  of  the  trough;  the 
upper  and  more  micaceous  group  of  rocks  tilling  the  synclinal 
centre  of  the  trough,  and  compressed  into  the  lesser  foldings 
which  it  exhibits,  by  the  lateral  force  of  the  wide  undulation 
within  which  it  has  beeti  caugnt  and  folded." 

§  27.  The  northern  belt  of  harder  gneiss  rocks  has  a  breadth 
of  about  half  a  mile  in  width  on  the  Schuylkill,  but  runs  to  a 
point  before  reaching  the  valley  of  the  Wissahickon.  only  two 
and  a-half  miles  to  the  eastward,  being  overlapjied  obliquely 
by  the  margin  of  I'aleozoic  rocks  ;  but  it  broadens  to  the  west- 
ward, until  at  Darby  creek  it  has  a  breadth  of  four  miles. 

§  28.  This  gneissic  belt  on  the  Scliuylkill  is  limited  to  the 
north  by  a  band  of  newer  strata,  detined  by  Rogers  as  Primal 
and  Auroral  in  an  altered  condition,  which  constitute  a  broad 
belt  exposed  for  some  miles  across  the  strike,  tin'iiiing  the 
Montgomery  valley,  and  are  overlaid  to  the  north-west  by  the 
Mesozoic  sandstones.  The  greater  part  of  this  breadth  is  oc- 
cupied by  limestone,  but  along  the  southern  border,  immedi- 
ately adjoining  the  gneiss,  are  some  crystalline  strata  described 
by  Kogers  as  altered  I'rimal,  and  as  consisting,  at  the  base,  of 
what  he  called  the  semi-porphyroidal  group,  a  thiidy  laminated 
hornblendic  gneiss,  liaving  a  maximum  thickness  of  300  feet, 
and  overlaid  by  a  band  of  about  200  feet  of  talcose  and 
micaceous  slate,  holding  garnets.  To  this  succeeds  a  white 
([uartzose  rock  containing  felds})ar,  tourmaline  and  mica,  re- 
garded by  him  as  constituting  the  third  member  of  the  Primal 
series,  and  from  100  to  300  feet  in  thickness.  These  strata  are 
described  and  figured  by  Rogers  in  sections  on  pages  156,  104, 
165,  vol.  I,  Geology  of  Pennsylvania,  where  they  are  repre-* 
sented  as  nearly  or  quite  vertical  in  attitude  along  the  north- 
ern side  of  the  gneiss,  and  as  passing  northward,  in  some  cases 
after  certain  undulations,  beneath  the  Auroral  limestones.  This 
broad  band  of  Primal  and  Auroral  rocks  does  not  extend  much 


SERPENTINES    AND   STKATITKS. 


E.   lo 


to  the  eastward  of  tlie  Schuvlkill :  but  to  the  north  of  a  narrow 
belt,  represented  as  Primal,  stretching  eastward  to  the  J)ela- 
ware  just  below  Trenton,  there  extends  the  whole  distance 
along  the  southern  border  of  the  Mesuzoic  a  ran>;e  of  gneiss, 
regarded  by  Rogers  as  identical  with  that  whicii,  upon  the 
Seliuylkill,  forms  the  northern  ilivision  of  the  Stmthern  gneissic 
district.  At  the  falls  of  the  Delaware,  at  Trenton,  according 
to  him,  the  rock  is  a  dark  hornblendic  gneiss,  di[»ping  steeply 
south-south-east. 

§  29.  We  have  seen  that  our  author  (§  2G)  looks  upon  the  whole 
of  this  Southcri  gneissic  region  as  made  up  of  two  groups  of 
strata,  a  lower  and  more  feldsjiathie  series,  apjicaring  on  the  two 
sides  of  the  basin,  and  a  newer  and  more  micaceous  series,  oc- 
cupying the  centre  of  the  synclinal.  It  might  be  supposed 
that  these  two  divisions  correspond  respectively  to  the  Ily- 
pozoic  and  Azoic  series  of  tlie  autiior,  but  the  whole  suc- 
cession is  described  under  the  iiead  of  the  older  crystalline 
Gneissic  strata,  or  the  llypozoic  series  ;  which  is  elsewhere  said 
to  ''consist  of  true  gneiss  in  all  its  varieties,  quartzose,  felds- 
pathic, micaceous  and  hornblendic,  with  fully  developed  or  typi- 
cal mica-schist,  talc-schist,  chlorite-schist  and  the  other  crystal- 
line schists  usually  classed  with  the  genuine  or  older  (llypozoic) 
gneiss."  (Vol.  II,  p.  7-14.) 

§  30.  With  regard  to  the  belt  of  magnesian  rocks  in  the  gneis- 
sic region  of  the  Schuylkill,  he  says  :  '"Viewing  the  steatite  as  a 
stratified  rock  of  the  mica-slate  group,  we  may  reasonably  re- 
gard it  as  having  L>een  metamorphosed  to  its  i>resent  condition 
and  structure  by  infusion  of  magnesian  matter  from  the  dyke 
of  serpentine,  which  everywhere  adjoins  it."  (Vol.  I,  p.  72.) 
Elsewhere  he  describes  a  similar  belt  of  rocks,  a  little  farther 
to  the  west,  as  comprising  both  "true  injected  ser[)entine  and 
serpentinous  steatitic  talc-schist." 

The  reader  is,  however,  soon  after  perjtlexed  to  find  that  the 
serpentines  and  steatites  of  the  Schuylkill,  and  indeed  of  all 
the  region  south  of  the  limestone  valley  of  Montgomery  and 
Chester  counties,  are  described  in  detail  at  the  end  of  the  chapter 
on  the  Primal  rocks  (Vol.  I,  \,\i.  107-172,);  leaving  it  to  be  in- 
ferred, though  nowhere  distinctly  stated,  that  these  are,  in  some 
way,  related  to  the  Lower  Primal  (which  we  iiave  seen  to  be 


tr. 


16  E. 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


synoDj-moijs  in  the  nomencliiturc  of  Rogers  with  tlic  Azoic,) 
ratlier  tluiu  to  the  Il^'pozoic  series. 

§  31,  It  iiuiy,  however,  he  noted  that  of  the  serpentine  areas 
represented  on  his  geological  map,  one,  that  of  the  Schuylkill, 
is  placed  wholly  within  the  Hypozoic,  and  another,  that  of 
Texiis  nciir  the  Susquehanna,  in  the  Azoic  or  I'rinial.  Those 
of  South  Valley  Hill,  of  the  I'aoli,  as  well  as  the  serpentine 
belt  along  the  Marvland  state-line,  are  each  described  as 
bounded  to  the  southward  by  massive  gneissic  rocks,  which,  io 
the  case  of  the  last  named,  appear  to  be  unconformable  in  dip 
with  the  serpentine.  To  the  northward,  the  last  two  belts  are  said, 
to  be  bounded  by  talcose  or  micaceous  and  argillaceous  slates, 
including  the  roofing-slates  of  Peach  Bottom,  regarded  as 
Lower  Primal.  In  the  case  of  the  serpentine  and  stcatitic  belt 
of  South  Valley  Hill,  the  gneiss  is  again  repeated,  scp.arating 
it  from  a  limestone  valley  to  the  north.  The  Unionville  ser- 
pentine region  is  described  as  being  wholly  in  the  midst  of 
micaceous  and  talcose  schists.     (Vol.1,  pp.  1G7-172.) 

§  32.  In  cxi)lanation  of  this  it  must  be  remembered  that  all 
the  true  serjtentines  were  looked  upon  by  Rogers  as  intruded 
igneous  masses,  the  eruption  of  which  was  accompai:icd  by  an 
infusion  of  magncsiiui  matter,  which  had  changed  into  talcose 
and  serpentinous  rocks,  the  micaceous  schists,  both  of  the 
Azoic  and  Hypozoic  series.  The  more  micaceous  portions  of 
the  Hypozoic  are,  moreover,  declared  to  rcsenibio  so  closely 
the  micaceous  schists  of  ;ho  Azoic  "in  mineral  aspect  and 
structure  as  to  balllo  all  o'lcmpts  at  distinguishing  them  litho- 
logically." 

§  33.  This  point  is  further  discussed  near  the  close  of  our 
author's  second  volume,  where,  in  a  sketch  of  the  geolog}-  of  tho 
United  States,  after  referring  to  the  labors  ot  the  Canada (jico- 
logical  Survey,  which  had,  in  1847-1852,  pointed  out  the  exist- 
ence of  a  series  of  crystalline  schists  intermediate  between  tho 
ancient  gneissic  system  and  the  Paleozoic  series,  ho  refei's  to 
the  investigations  of  I'rof  William  B.  Rogers  in  Virginia,  who 
had,as(>arly  as  1830,  recognized  a  similar  series  east  of  the  Blue 
Kidge  in  Virginia.  These  rocks,  extending  along  the  "Atlantic 
slope  of  the  southern  stales,"  were  sai<l  to  consist  "of  various 
coarse  talcoid  and  chloritie  schists,  semi-porphyritic  arenaceous 


ALTERED  PALEOZOIC  OF  ROGERS. 


E.  17 


ho- 

nir 
lio 
o- 

st- 
ho 
to 

Iho 

|uo 
ic 

13 
IS 


* 


* 


grits  and  congloraeratea,  and  jaspory  and  plumbaginous  slates, 
al!  penetrated  extensively  by  metalliteroua  veins  and  dykes, 
particularly  of  gold-bearing  quartj^,  and  by  d3'kesof  porpbyritic 
greenstone,  epidote  and  otber  older  plutonic  rocks.  * 
Kovcrtbeless  it  is  impossible  in  tbe  present  early  stage  * 
to  define  witb  any  accuracy,  over  large  spaces  of  country,  the 
unper  a7id  loicer  limits  oi' th\s  more  or  less  independent  semi- 
•.ietamor])bio  system,  and  it  is  especially  difRcult,  at  present,  to 
seiiarateit  from  tbeoverlyinggcjiuine  Paleozoic  formations,  into 
wbicli,  indeed,  this  series  may  probably  graduate,  in  many  dis- 
tricts, witbout  any  pbyaical  break  at  all.  The  Azoic  sedi- 
ments were  succeeded  by  the  Paleozoic,  in  some  quarters  appa- 
rently with,  iti  some  witbout,  tbe  interrui)tion  of  a  disturbatice 
of  levels,  witb  interru])tion8  amounting  to  mechanical  uncon- 
formity." 

§  84.  "  In  view  of  this  uncertainty  respecting  the  true  limits 
of  tbe  older  groups,  no  attempt  is  bere  made  to  define  in  the 
regions  of  tbe  metamor[»bic  rocks  more  than  two  systems — the 
genuine  or  older  gneissic,  and  tbe  later  or  semi-metamorphic 
strata;  tbe  latter  including  both  tbe  supposed  middle  series  or 
true  Azoic  strata,  and  the  proper  Paleozoic  formations  altered 
in  type.  This  merging  of  the  latter  two  groups  under  one 
series  is  ma<le  indispc -sable  by  the  absolute  imj>ossibility  of 
ascertaining  at  present  the  true  base  of  tbe  Paleozoic  system ; 
for  the  history  of  geology  forbids  us  to  believe  that  research 
has  yet  detected  the  actual  horizon  of  the  dawn  of  animal  and 
vegetable  life  upon  our  globe."     (Vol.  II,  page  745.) 

§  35.  The  crystalline  condition  which  characterizes  the  in- 
termediate or  so-called  Azoic  series,  in  some  cases,  according  to 
Rogers,  extends  upward,  embracing  all  the  members  of  the 
Paleozoic  series  mentioned  in  §§7-l\  We  arc  told  tliat  the  Primal 
white  sandstone  is  occasionally  converted  into  a  vitreous 
quartzite,  and  at  other  times  into  a  "  stratified  i'eldspar  rock," 
while  "the  limestones  at  the  passage  of  the  Primal  into  the 
Auroral,"  or  as  elsewhere  defined,  at  "the  alternations  of  Primal 
slate  and  Auroral  limestone,  are  converted  into  crystalline  dolo- 
mite or  marble,  with  seams  and  partings  of  crystalline  scaly 
talc."  The  Auroral  limestone  is  said  to  become  "a  white  and 
2— K. 


m 


18  E 


SPECIAL    REPORT.       T.  STERRY    HUXT,   1875. 


mottled  marble,  with  semi-plumbagitious  laminae" ;  while  the 
gray  sandstone  of  the  Matinal  series  becomes  "a  highly  in- 
durated Bcmi-porphyritic  grit,"  and  the  Matiiuil shale''  a  serai- 
crystalline  clay-hlate,  partially  talcose  or  micaceous." 

§  'in.  In  illustration  of  these  statements  we  may  cite  the  ac- 
count given  by  liogers  of  an  area  of  crystalline  rocks  met  with 
in  the  South  Mountain,  to  the  south  of  the  Susquehanna  river. 
The  strata  are  described  as  chietiy  of  three  classes  ;  one  being 
a  group  of  chloritic,  micaceous  and  talcose  slates,  with  hard 
green  rocks  abounding  in  epidote  and  quartz,  sometimes  with 
a&bestus,  and  containing  occasionally  small  portions  of  copper 
ores  and  of  native  co[)per.  A  second  class  includes  several  va- 
rieties of  what  is  described  as  a  reddish  jaspery  rock  ;  elsewhere 
called  a  highlv  altered  jaspery  slate,  red  or  reddish-gray  in 
color,  and  sometimes  holding  s^iecks  of  red  I'oldspar  and  small 
veins  of  epidote.  In  addition  to  these  is  a  third  class,  of  gran- 
ular quartzites  or  sandstones,  sometimes  described  as  talcose 
and  (juartzose  conglomerates. 

§  37.  These  rocks,  which  rise  in  a  series  of  parallel  ridges  on 
the  south-eastern  border  of  the  great  valley  of  Auroral  lime- 
stone, were  l)y  Rogers  regarded  as  juembers  of  tlie  Primal 
aeries ;  the  reddish  jasper}'  strata  being  the  Primal  upper 
slates,  "greatly  modided  in  texture  by  the  intrusion  of  quartz, 
and  by  other  igneous  action  ;"  intrusive  greenstones  and  traps 
being  mentioned  as  occurring  m  the  series.  Elsewhere  we 
have  seen  that  the  Primal  white  sandstone  itself  was  supposed 
to  become,  by  alteration,  a  feldspar-rock.  To  the  Primal  lower 
slatej  are  referred  at  least  a  portion  ot  the  greenish  chloritic 
and  ejtidotic  rocks  of  the  region;  while  the  sandstones  with 
talcose  slates  are  supposed  to  represent  the  Primal  white  saiul- 
stone. 

§  38.  These  strata  present,  with  some  exceptions,  dips  to  the 
south-east,  often  at  high  angles,  and  the  structure  of  the  re- 
gion is  described  by  Kogers  as  a  series  of  folds,  with  inverted 
dips.  In  illustration  of  this  we  are  told  that  on  the  north- 
west side  of  the  mountain  the  Primal  upper  slates  are  found 
dijtjting  southward,  and  overlaid  by  the  Primal  sandstone  ; 
while  from  beneath  this,  on  the  crests  of  the  anticlinals,  a|)pear 
the  greenish  ejtidotic  strata  of  the  i'rimal  h)wer  slates.  Portions 


I 


ALTERED  MESOZOIC  OF  ROGERS. 


E.  19 


of  the  Auroral  limestone  are  found,  in  one  or  more  places,  in  the 
synclinal  folds  of  this  mountain-helt ;  and  in  one  locality  arc 
associated  with  the  hydrous  iron  ore  wliich  usually  accompanies 
this  limestone  series.     (Vol.  I.,  pp.  202-207.) 

§  39.  It  will  be  observed  that  under  the  head  of  eruptive  or 
igneous  rocks  Rogers  includes  the  so-culled  dykes  of  serpen- 
tine ;  and,  moreover,  that  the  greenstones  and  epid(»tic  rocks, 
which  are  abundant  in  many  parts  of  the  schistose  crystalline 
strata,  are  spoken  of  as  eruittive  or  plutonic  in  character;  while 
even  the  quartz  veins  found  cutting  the  strata  were  regarded  as 
of  igneous  origin.  It  is  moreover  suggested  that  the  Primal 
sandstone  itself  may  have  been  derived  ''from  the  great  dykes 
and  veins  of  auriferous  quartz,"  supposed  to  have  issued  "in  a 
melted  conditioTi  through  rents  and  fissures  in  the  earth's 
crust;  outgushing  bodies  of  this  quartz,"  chilled  by  contact 
with  cold  water,  having  been  broken  up  into  sand,  and  subse- 
quently spread  over  the  ocean's  bottom.     (Vol.   II,  page  780.) 

Elsewhere  he  speaks  of  a  belt  of  sparry  limestone  associated 
with  the  gneiss  of  the  Welsh  Mountain,  and  traced  for  a  mile 
and  a  half,  as  follows:  "Whether  this  limestone  is  a  true  ig- 
neous dyke  or  vein  of  carbonate  of  lime,  or  a  closely  compressed 
trough  of  sedimentary  limestone,  metamorphosed  by  heat,  I 
will  not  undertake  to  f^i^.y.^'  (Vol.  I,  page  90.)  These  extracts 
aiv  made  not  in  a  spirit  of  invidious  criticism,  but  because  we 
shall  have,  farther  on,  to  point  out  certain  erroi-s  with  regard  to 
these  crystalline  strata,  which  had  their  origin  in  the  ex- 
aggerated plutonic  views  of  the  author.  Tiiese,  however,  he 
shared  with  many  others  of  his  time. 

§  40.  This  notice  of  our  author's  account  of  the  crystalline 
roclvs  of  this  region  would  not  be  c()ni[)lete  without  reference 
to  the  su^iposed  altered  Mesozoic  sandstone,  found  associated 
with  several  deposits  of  iron  ores,  in  contact  with  the  gneiss 
of  the  Middle  district,  and  at  a  greater  or  less  distance  south  of 
the  border  of  the  great  belt  of  Mesozoi<^  rocks.  They  are,  ac- 
cording to  him,  connected  with  faults  or  dislocations;  "which 
are  so  many  rupture<l  synclinal  troughs,  enclosing  narrow  belts 
or  outcrops  of  a  material  which,  by  all  lithological  analogy,  can 
only  bo  referred  to  the  Middle  t^econdary  sandstone,  altered, 
more  or  less,  by  some  igneous  metanioriihic  agency,"  apparently 


4 


20  E. 


SPECIAL    RErOHT.       T.  STEKKY    HUNT,   1875. 


connected  with  the  supposed  folding-up  of  the  sandstone  (which 
has  a  moderate  dip  to  the  nortii-west  throughout  this  region) 
in  these  steep  and  overturned  synclinals. 

§41.  The  ore  in  these  deposits,  of  whicli  many  were  formerly 
mined  in  the  valley  of  Pickering  creek,  is  descrihcd  as  usually 
lying  hetween  gneiss  or  granite  on  the  one  side  and  a  layer  of 
altered  red  sandstone  on  the  other,  both  dijiping  at  pretty  high 
angles  to  the  south-eastward  ;  the  latter  highly  crystalline,  and 
holding  scales  of  ]»lumbago,  mica  and  specular  iron.  The 
somewhat  questioirible  nature  of  the  "lithological  analogy"  by 
which  these  crystidline  rocks  are  referred  to  the  Mesozoic,  be- 
comes evident  when  we  read  respecting  one  of  these  de|M)sit3, 
that  the  supposed  altered  sandstone,  froia  its  higiily  crystalline 
condition,  "greatly  puzzles  the  observer  to  determine"  whether 
it,  like  the  opposing  wall,  "is  gneiss,  or  a  highly  metamor- 
phosed form  of  the  argillaceous  red  sandstone."  Of  another 
adjacent  mine,  we  are  told  that  it  is  difficult  to  determine  in 
hand-specimens  whether  the  rock  is  an  altered  sandstone  or 
gneiss.  There  seems  no  foundation  for  the  notion  that  these 
crystalline  strata  on  either  side  of  the  ore  are  anything  else 
than  varieties  of  more  or  less  decayed  gneissic  rock. 
Thi^  ores  of  these  mines  are  the  usual  varieties  of  brown 
hematite,  sometim.es  with  oxide  of  manganese,  and  occasionally 
with  a  little  pyrites.     (Vol.  1,  page  80-90.) 

§  42.  From  the  foregoing  analysis  of  the  descriptions  given  by 
Rogers,  it  is  clear  that  he  recognized  in  south-eastern  Pennsyl- 
vania cr3'8taHine  stratified  rocks  pertaining  to  not  less  than 
seven  distinct  geological  horizons,  and  presenting  marked  lith- 
ological  dillerences.  Two  of  these  divisions  belong  to  the  lly- 
pozoic,  two  to  the  Primal  series,  and  one  each  to  the  Auroral, 
Matinal  and  Mesozoic.     They  areas  follows,  in  ascending  order: 

1°.  Lower  Ili/pozoic. — We  have  seen  that  the  llypozoic  or 
Gneissic  seriew  in  the  Southern  district  was  supposed  to  consist 
of  a  lower  and  an  uj)per  portion.  (§  26.)  The  lower  division 
is  described  as  c(»nsisting  ol  luird  ([uartzo-feldspathic  and  horn- 
blendic  rocks,  chiefly  granitoid  and  syenitic  gneisses,  with  lit- 
tle or  no  mien. 

2°.  Upper  I^t/pozoic. — The  upper  portion  is  described  as 
highly  micucoous  gneiss,  with   a  great  amount  of  micaceous 


ALTKIJKD   PALEOZOIC  OF  FIOGERS 


E.  21 


schist,   and  as  iu'iludiug  also  chloritie,  talcose  and  serpentinic 
rocks. 

3°.  Lower  Primal. — The  Primal  also  is  divided  into  two  por- 
tions, which  are  litliologically  widely  dissimilar.  Ot  these  the 
Lower,  or  so-called  Azoic,  includes  the  Primal  crystalline 
schists,  and  the  succeed in«^-  Primal  lower  slates,  which  closely  re- 
semhle  them ;  the  series  consistiiii;'  chiefly  of  micaceous,  chloritie 
and  talcose  schists,  often  hi<::;hly  silicious,  together  with  hard 
green  rocks,  abounding  in  ejiidote.  This  Lower  Prmial  series  is 
declared  to  he  often  not  distingnisluihle  from  the  Upper  Hypo- 
zoic,  and  like  it  contains  serpentine  and  it      ssociated  rocks. 

4°.  Upper  PrimaL — The  Upper  Primal  slates,  when  altered, 
are  supposed  to  assume  a  character  totally  unlike  their  normal 
one,  and  to  become  in  great  part  a  very  hard  red  or  red- 
dish-gray jas])ery  rock,  often  more  or  less  schistose,  includ- 
ing red  feldspar,  and  occasionally  seams  of  ejiidote.  (§3(3).  The 
Primal  white  sandstone  itself,  we  are  told,  sometimes  becomes 
altered  to  a  stratified  feldspar-rock  ;  but  for  want  of  farther  de- 
tails it  is  not  certain  whether  this  is  to  be  confounded  with 
the  jaspery  feldspathic  forui  of  the  Primal  upper  slates. 

5°.  Auroral. — Under  this  head  may  be  included  the  altered 
Auroral  limestones,  and  their  included  schistose  beds  (§  35). 

G°.  Matinal. — The  supposed  altered  rocks  of  the  Mutinal  se 
ries  have  already  been  noticed  (§  35). 

7°.  Mesozoic. — The  supposed  conversion  of  portions  of  the 
Mesozoic  strata  into  a  rock  difficult  to  distinguish  from  the 
llypozoic  gneiss,  has  also  been  referred  to  (§  41). 

§  43.  My  object  in  thus  attempting  to  condense  and  systema- 
tize some  of  the  scattered  details  from  the  reports  of  Prof.  Pog- 
ers  regarding  the  crystalline  rocks  of  this  region  will  be  made 
more  apiiarent  in  the  succeeding  chapters. 

While  some  of  the  conclusions  appear  to  me  inadmissible, 
the  value  of  the  great  mass  of  minute,  conscientious  ;nnl  ex- 
act observations  which  ho  has  accumulated,  very  many  of 
which  1  have  personally  verified,  cannot  be  over-estimated  by 
the  student;  wlio  njust  make  them  the  starting-point  in  any  new 
attempt  to  advance  our  geological  knowledge  of  this  curious 
and  compli(;ated  region. 

§  44.  It  may  here  be  proper  to  allude  to  the  geological  map  of 


"hi 


22  E. 


SPECIAL  REPORT.      T.  STERRY  HUNT,  1875. 


Canada,  and  of  the  eastern  United  States  as  far  south  as  the  Po- 
tomac, published  by  Sir  William  E.  Lo<;an  in  the  Atlas  to  the 
Geology  of  Canachi,  in  1864.  The  Highlands  of  the  Hudson 
having  been  referred  to  the  Laurentian  system,  the  South 
Mountain,  recognized  by  Rogers  as  a  prolongation  of  these,  was 
correctly  represented  as  belonging  to  that  ancient  system  ;  and 
in  the  enlarged  edition  of  the  same  map,  published  in  186(3,  the 
similar  gneiss  of  the  Middle  district  of  llogers  likewise  re- 
ceived the  name  of  Laurentian.  The  whole  southern  region, 
including  both  the  Ilypozoic  and  Azoic  series  of  Rogers,  was, 
however,  by  Logan  represented  in  the  map  of  1861  as  belong- 
ing to  the  so-called  Quebec  group.  This,  in  the  edition  of  1866, 
was  modified  ;  while  the  whole  of  the  Ilypozoic  series,  as  de- 
fined by  Rogers,  was  still  called  the  Quebec  group,  the  Azoic 
series  was,  with  singular  inconsequence,  referred  to  the  Potsdam. 
This  curious  treatment  of  the  scientific  labors  of  another,  in 
thus  interpreting  the  geology  of  a  region  which  he  had  never 
examined,  can  only  be  described  as  an  error  on  the  part  of  the 
compiler  of  the  geological  map  in  question. 


\H 


{.III 


iMl 


CHAPTER  n. 


^'ii 


HISTORICAL    SKETCH. 

§  45.  The  history  of  the  ancient  rocks  of  eastern  Pennsyl- 
sylvani.'t  is  so  closely  connected  with  that  of  tlieir  extension 
northwards  throujrh  New  York,  New  England  and  Canada, 
that  an  intelligent  understanding  of  tlie  various  questions  to 
which  their  study  gives  rise,  is  only  possible  to  those  who  are 
acquainted  with  the  progress  of  our  knowledge  of  the  geology 
of  these  regions,  from  the  beginning  of  the  century  down  to 
our  own  time.  It  will  therefore  be  the  object  of  the  present 
and  the  succeeding  chapter  to  present  an  outline  of  the  history 
of  geological  research  in  the  regions  mentioned. 

§  4G.  The  tirst  distinct  attenqtt  to  classify  the  rock-formations 
of  eastern  North  America  was  that  made  by  William  Maclure, 
who  published  a  geological  map  and  description  of  the  United 
States,  in  1809,  and  asecond  tiine,  in  1817,  in  a  revised  edition, 
which  appeared  in  the  Transacitions  of  the  American  Philo- 
80|»hical  Society,  (vol.  1,  new  series,)  as  a  memoir  of  ninety 
pages,  with  a  colored  geological  map  and  sections.  He  divicled 
the  rocks  into  five  classes:  Prinutivo,  Transition,  Secondary, 
Old  Ked  Sandstone  and  Alluvial.     The  lirst  of  these  included 

[E.  23] 


24  E. 


SPECIAL   REPORT.      T.  STERRY    HUNT,  1875. 


i!i 


ii! 


If » 


all  the  crystalline  rocks  of  the  great  Atlantic  belt,  aucl  those  of 
northern  New  York — no  allusion  being  made  to  those  west  of 
the  great  lakes  and  the  Mississippi.  Of  the  "  gneiss  formation  " 
of  the  Primitire,  he  remarks  that  it  includes,  in  a  great  many 
places,  beds  from  three  to  three  hundred  feet  thick,  of  a  large- 
grained  granite,  running  and  dipping  like  the  gneiss.  "  These 
beds  are  mixed  and  occasionally  alternate,  in  the  same  gneiss, 
with  the  primitive  limestone,  the  beds  of  hornblende  and  horn- 
blende-slate, serpentine,  magnetic  iron  ore,  etc."; — a  very  good 
description  of  the  gneissic  and  granitoid  rocks  of  the  Lauren- 
tian  series. 

§  47.  The  Transition  class  of  Maclure  embraced  the  great  belt 
of  disturbed  uncrystalline  rocks  extending  along  the  west  side 
of  the  Primitive,  from  Lake  Cluimplain  to  Georgia.  Li\  it  were 
comprised  the  anthracite-bearing  strata  of  Khode  Island  and  of 
Pennsylvania  ;  while  the  bituminous  coal  regions  were  include<l, 
with  the  horizontal  paleozoic  rocks  of  New  York,  and  the  whole 
region  west  to  the  Mississippi,  and  beyond,  in  the  Secondary 
division.  A  second  and  narrow  Transition  belt,  on  the  south- 
east slope  of  the  Blue  Ridge,  was  noticed  as  extending  from 
the  Delaware  to  the  Yadkin;  including  the  limestone  and  other 
associated  schists  of  the  Lancaster  and  Chester  valleys  in 
Pennsylvania.  The  Mesozoic  of  the  Atlantic  belt  was  desig- 
nated as  Old  Red  Sandstone  ;  while  the  newer  Secondary  and 
Tertiary  of  the  coasts  was  included  under  the  Alluvial  class. 

§  48.  The  labors  of  Amos  Eaton  mark  a  new  epoch  in  Ameri- 
can geology,  and  have  left  a  durable  impression  on  the  science. 
In  1824  api)eared,  under  the  patronage  of  Stephen  Van  Rens- 
selhier,  Eaton's  "  Geological  and  Agricultural  Survey  of  the  Erie 
Catial,''  with  an  engraved  section  representing  the  formations 
from  Lake  Erie  to  Boston;  to  which  was  added  a  colored  prolile 
of  the  rocks  from  Boston  as  far  west  as  Plainfield,  Massachu- 
setts; prepared  with  notes,  by  p]dward  Hitchcock.  This  work, 
and  the  "Geological  Text-book"  of  Eaton,  of  which  the  second 
edition  appenred  in  1832,  are  the  sources  from  which  we  may 
learn  the  geological  views  of  tliis  original  and  ingenious  inves- 
tigator. 

§  49.   He  announced,  as  one  of  the  im|»ortant  discovv^iles  of 
himself  and  his  assistants,  the  conclusion  that  each  of  the  great 


PRIMITIVE    ROCKS    OF   EATON. 


E.  26 


geological  groups  in  Euroiie,  as  well  as  in  America,  "  cora- 
inenccd  with  carboniferous  slate,  and  terminated  with  calcare- 
ous rocks,  having  a  middle  formation,  the  centre  of  which  is 
quartzose."  (Text-book,  page  23).  This  is  remarkable  as 
the  first  recognition  of  the  natural  law  of  cycles  in  sedimenta- 
tion, now  so  well  understood.  The  rocks  of  North  America 
were  divided  into  five  great  series:  I,  Primitive  :  II,  Transi- 
tion ;  III,  Lc.wcr  Secondary  ;  IV,  Upper  Secondary  ;  V,  Ter- 
tiary— each  of  which  was,  according  to  him,  a  more  or  less 
complete  triad;  having  a  carboniferous  formation  (1)  at  the 
base,  a  silicious  formation  (2)  in  the  middle,  and  a  calcareous 
formation  (3)  at  the  sunnnit.  It  will  he  understood  that  by 
the  term  "carboniferous,"  he  moans  nothing  more  than  a  slaty 
or  argillaceous  formation,  such  as  is  accom[)anied  by  carbona- 
ceous matters  at  various  horizons.  A  careful  analysis  of  his 
application  of  this  system  of  classification  to  the  rocks  of  New 
York  and  New  England,  will  be  found  to  throw  light  upon 
some  questions  in  geology,  which  are  still  obscure  and  unsettled. 
§  50.  The  Primitive  series  of  Eaton  had  for  its  first  or  carbon- 
iferous division,  (I,  I)  micaceous,  taleose  and  chloritic  slates, 
with  hornblendic  rocks,  granite  or  gneiss ;  the  pluml)ago  met 
with  in  this  division  justifying,  according  to  liim,  the  name  of 
a  carboniferous  formation.  The  second  division  (I,  2)  was  the 
granular  quartz  rock  of  western  New  England;  and  the  third 
(I,  3)  the  granular  limerock,  including  the  marbles,  of  the  same 
region.     This  Trimitive  series  was  supposed  to  be  destitute  of 


organic  remains. 


§  51.  Besides  the  gneissic  region  of  New  England,  Eaton  had 
studied  those  of  the  Highlands  of  the  Hudson  and  of  northern 
New  York.  To  the  latter  region,  now  known  as  the  Adiron- 
dacks,  he  gave  in  1824,  "the  general  name  of  Macomb's  Moun- 
tains;" a  large  part  of  the  district  being  then  known  as  Ma- 
comb's Purchase  (Geol.  Sur.,  page  43).  In  1832,  he  had  already 
examined  a  collection  of  the  rocks  from  Lake  Huron  to  Mon- 
treal, collected  from  "the  mountain  ridge  which  runs  along  the 
north  side  of  the  great  chain  of  lakes  ;"  and  another  series  "  pre- 
senting the  entire  geology  of  the  whole  circuit  of  Lake  Su- 
perior." From  the  study  of  these  he  announced  that  "the  Ma- 
comb-Mountain  range  of  Primitive  rocks  extends  in  a  north- 


2(1  K 


SPECIAL    REPoUT.      T.  STERUY    HUNT,  187.'). 


3 


t- 


weat  direction,  formiiii^  the  north-eastern  boundary  of  the  great 
lakes,  at  least  to  the  distance  of"  one  thousand  miles  from  the 
St.  Lawrence  at  Oi>;densburgh."  lie  remarked  a  great  re- 
semblance between  the  rocks  of  the  Macomb  Mountains  and  the 
Highlands  of  tlie  Hudson  ;  adding,  "they  are  remarkably  char- 
acterized, and  distinguished  from  the  Primitive  rocks  of  Xew 
England,  and  most  European  districts,  by  their  great  propor- 
tion of  hornblende-rocks,  and  by  the  presence  of  tabular-spar, 
grains  of  inters[»ersed  serpentine,  coccolite,  colophonite  and 
masses  of  diallage."  (Text-book,  pages  68  and  6.)  "The 
gneips  (of  the  Macomb  Mountains)  is  more  nearly  in  a  hori- 
zontal position  than  is  usual  for  rocks  of  gneiss  in  New  Eng- 
land."    (Geol.  Survey,  i>age  42.) 

§  52.  We  come  next  to  his  second  or  Transition  series,  of 
which  the  lower  division  (II,  1)  is  an  "Argillite"  formation,  con- 
sisting of  clay-slate  (including  roofing-slate)  and  a  gritty  va- 
riety, designated  as  wacke-slate.  Both  of  these  are  described 
as  inclined  in  their  attitude;  the  wacke  having  "the  same  in- 
clination with  the  argillite,  and  diftering  widely  from  the  hori- 
zontal or  First  Gray  wacke."  This  latter  constitutes  the  second 
division  of  the  Transition  series  (II,  2)  and  consists  of  "Gray- 
wacke-slate,"  described  as  a  fine  argillaceous  sandstone,  and  of 
"Millstone  grit  and  gray  rubble,"  more  or  less  conglomerate. 
The  tliird  division  (II,  3)  comprises  the  Sparry  limestone, 
found  east  of  the  Hudson,  the  Calciferous  sand-rock,  identical 
with  that  formation  in  the  New  York  series,  and  the  Transition 
or  Metalliferous  lime-rock.  Under  this  latter  name,  borrowed 
from  Bakewell,  were  comprised  the  Birdseyeand  Trenton  lime- 
stones ;  the  localities  of  which,  and  some  of  their  organic  re- 
mains, are  described  by  Eaton. 

§  53.  To  this  succeeds  the  Lower  Secondary  series,  having 
at  its  base,  as  before,  a  carboniferous  division,  (III,  ])  described 
as  the  "  Second  gray  wacke  slate ;"  which  rests  upon  the  "  Transi- 
tion limerock"  (Trenton.)  This,  which  is  clearly  identified  as 
the  Utica  and  Ijoraine  formations,  is  overlaid  by  a  second  Mill- 
stone grit,  which  is  the  Oneida,  (111,  2)  and  is  described  as 
passing  beneath  the  calcareous  division,  (III,  3)  which  includes 
the  Geodiferous  limerock  (Niagara)  and  the  Corniferous  or 
Cherty  limerock  (Lower  and  U[)per  Helderberg.) 


TRANSITION    AND   SECONDARY    ROCKS    OF    EATON.         E.    27 


§  ")4.  The  red  sandstones  and  shales  of  the  Medina,  the  iron- 
bearing  strata  of  the  Clinton,  and  the  saliferous  and  g^-psifer- 
ous  marls  of  the  Onondaga,  with  the  overlying  Water-lime  beds, 
were  by  Eaton  regarded  as  a  "  subordinate  series  embraced  in 
tlie  third  regular  series."  With  these  red  rocks  he  united  cer- 
tain red  l)eds  in  the  Catskills,  as  well  as  the  red  sandstones  of 
the  Mcsozoic  of  New  York,  Xew  Jersey  and  the  Connecticut 
valley.  The  disappearance,  to  the  eastward,  of  the  great  mass 
of  red  str.ita  which,  in  central  Xew  York,  is  intercalated  at  the 
base  of  the  ilelderberg  limestones,  is  noticed  by  Eaton.  The 
Cherty  Secondary  limestone  is  said  to  be  separated  at  Bethle- 
hem Xew  York,  by  only  sixty  feet  of  graywacke-slate  from  the 
Transition  limestone,  and  to  come  m  contact  with  it  in  Catskill 
in  (Jreene  county.  These  limestones  of  the  Lower  Secondary  se- 
ries, it  was  shown,  underlie  alike  the  bituminous  coals  of  west- 
ern Pennsylvania,  and  the  anthracites,  which  latter  were  thus  re- 
moved from  the  Transition  series,  to  wdiich  they  had  been  re- 
ferred by  Maclure.  Eaton  showed,  moreover,  from  their  fossil 
plants,  that  these  coals,  of  both  kinds,  belonged  to  the  same 
geological  horizon  with  the  coals  of  Europe. 

§  5 J.  The  coal  measures  were  placed  in  the  carboniferous  di- 
vision of  Katon's  Upper  Secondary  series,  (IV,  1)  which  also  in- 
cluded the  sandstones  of  the  Erie  division  of  the  Xew  York 
scries  ;  while  the  sandstones  of  the  Catskill  Mountain  were 
made  the  second  division,  (IV,  2)  and  the  third  (IV,  3)  was 
supposed  to  be  represented  by  certain  coralline  limestones  in  the 
Ilelderberg.  It  is  obvious  that  Eaton  here  fell  into  errors  in 
the  succession  of  strata,  which  make  it  no  longer  profitable  to 
follow  him  ;  and  we  now  return  to  the  consideration  of  his 
Transition  and  Lower  Secondary  series. 

§  56.  The  Argillite  formation  of  Eaton,  which  is  the  lowest 
division  of  his  Transition  series,  (II,  1)  is  said  by  him  to  form 
"  the  bed  and  banks  of  the  Hudson,"  and  to  appear  on  the  line 
of  section  described  by  him  in  his  "  Geological  Survey,"  ibr  a 
breadth  of  about  twent}^  miles,  from  Williamstown  Mountain, 
in  Massachusetts  to  three  miles  west  of  Coboes  Falls,  on  the 
Mohawk  ;  where  it  disappears  beneath  the  overlying  rocks. 
The  clay  slate  of  the  formation  appears  to  the  eastward,  in  the 
mountain  mentioned,  but,  along  the  section,  is  concealed  in  great 


I 


If 


m 


:  1 

i 

]  i 

'  1 
i    ■; 

\    1 

28  K. 


SPECIAL  REPORT.   T.  STERRY  HUNT,  1875. 


part  beneath  the  coarser  sandy  wucke-slate.  The  two,  how- 
ever, are  considered  as  parts  of  the  same  formation,  as  they 
both  present  tlie  same  angle  of  inclination.  lie  is  careful,  in 
this  connection,  to  distinguish  between  the  attitude  of  the 
stratum,  and  that  of  the  laminse  of  the  slate,  wliicli  are  de- 
scribed as  forming  an  angle  with  the  former.  (Gcol.  Sur.,  07.) 
§  57.  This  inclined  wacke-slate,l)olonging  to  the  Argillite  for 
mation  (II,  1)  is  carefully  distinguished  from  the  graywacke 
slate,  the  lower  member  of  the  First  gray  wacke  formation  (II, 
2)  already  noticed;  of  which  it  is  said  "this  slate  is  nearly  hori- 
zontal, and  lies  immediately  upon  the  inclined  edges  of  tlie  Ar- 
gillite, from  Canada  to  Georgia.  It  is  remarkably  curved  and 
bent  on  the  Mohawk  between  the  Cohoes  and  Scbenectad}',  at 
Saratoga  lake,  and  at  the  entrance  of  the  Delaware  and  Hud- 
son canal."  He  adds,  in  a  note,  that  "  while  European  geolo- 
gists have  described  a  change  of  direction  at  the  meeting  of  the 
Lower  and  Upper  Secondary',"  in  which  the  latter  rests  hori- 
zontally upon  the  inclined  edges  of  the  former,  in  iS'orth 
America  this  change  takes  place  at  the  meeting  of  the  Argillite 
and  the  First  graywacke."     (Text  Book,  page  74.) 

§  58.  The  place  of  this  First  or  Transition  graywacke  (II,  2 
was,  according  to  Eaton,  between  the  Argillite  formation  (II,  1) 
and  the  Transition  limestones  (II,  3.)  Of  these  latter,  the  Cal- 
ciferous  eandrock  and  the  succeeding  limestones  were  not  shown 
to  rest  upon  the  Argillite ;  and  in  fact,  as  we  now  know,  are 
found,  in  the  localities  familiar  to  Eaton,  directly  upon  the  Prim- 
itive gneiss.  With  them  was,  however,  included  the  Sparry 
limestone,  known  only  in  the  eastern  part  of  the  state,  lie 
moreover  descriljes  numerous  larg-e  and  small  massi's  of  sand- 
stone  and  limestone  as  occurring  included  between  the  lamiiue 
of  the  Argillite,  near  the  Cohoes  Falls,  and  towards  the  delta  of 
the  Mohawk.  These  were  regarded  as  small  portions  of  the 
First  graywacke  and  the  Transition  limestone;  which, he  con- 
ceived, must  have  fallen  into  their  places  between  the  laminae 
of  the  Argillite,  while  this  rock  was  in  a  soft  state.  The  shelly 
(i.  e.  fossiliierous)  Transition  limestone  described  by  Eaton  as 
occurring  at  Becraft's  Mountain  near  Hudson,  is  now  known 
to  belong  to  his  Lower  Secondary  limestone  (III,  3j;  it  being 
of  Lower  llelderbery;  ay;e. 


^: 


TRANSITION    AND   SECONDARY    ROCKS    OF   EATON.         E.    29 


§  59.  Eaton  noticert  that  the  acidulous  carbonated  mineral  wa- 
ter olitaincd  bj  boring  at  u  doptli  of"  480  feet  in  Albany,  is  found 
in  the  ArgiHite,and  sup)p09es  thattlie  similar  waters  of  Saratoga 
(now  saifl  to  issue  from  the  Calciferous  sand-rock)  have  a  like 
source.  In  this  connection  it  is  well  to  recall  the  acidulous  min- 
eral spring  found  in  South  Argyle,  Washington  county,  also  in 
the  retiion  of  the  Arjrillito. 

This  Argillite  was  described  as  containing  a  flinty  slate  or 
Lydian  stone,  sometimes  green  and  jaspcr-likc,  beds  of  which 
abound  on  the  Hudson  near  Albany,  and  for  forty  miles  below. 
(Geol.  Survey,  pp.  69-70.) 

§  GO.  We  have  seen  that  Eaton  described  a  Second  graywacke, 
conbtitutinfj  the  lower  and  middle  divisions  of  the  Lower  Sec- 
ondary  ,and  made  up, like  the  First,  of  an  underlying  slate  ([II, 
1)  and  an  overlying  sandstone  and  conglomerate;  (HI,  2)  both 
of  which  are  declared  to  be  scarcely  distinguishable  from  the 
members  of  the  First  graywacke,  except  by  the  fact  that  they 
overlie  the  Transition  limestones  (II,  3).  This  Second  gray- 
wacke evidently  corresponds  to  the  Iltica,  Loraine  and  Oneida 
formations  of  the  present  n  lUienclature,  and  thus  has  its  recog- 
nized position  in  the  New  "    >rk  series. 

§  61.  With  regard  to  the  i  st  grayw  acko,  we  have  seen  that 
the  slate  which  forms  its  ii.wer  member  is  said  to  rest 
in  a  nearly  horizontal  attitude  on  the  inclined  Argillite 
formation,  in  many  localities  to  the  west  of  the  Hudson  Kiver. 
On  the  eastern  side  of  the  river  the  First  graywacke,  in  its 
completeness,  is  largely  developed.  "  It  is  seen  resting  on  the 
Argillite,  near  Col.  Worthington's  on  the  Little  Hoosic,  near 
the  east  line  of  Rensselaer  county.  On  ascending  the  western 
hill  or  ridge,  the  graywacke-slate,  rubble  and  millstone-grit 
are  found  in  succession.  This  ridge  extends  from  Canada 
through  the  state  of  Vermont,  Washington  county,  and  Rensse- 
laer and  Columbia  counties,  and,  crossing  the  Hudson  River, 
forms  the  vast  mountains  of  millstone-grit  called  Shawan- 
gunk."  Elsewhere  we  are  told  that  the  rubble  or  conglomerate 
of  the  First  2:raywacke  "forms  the  highest  ridges  between  the 
Massachusietts  line  and  the  Hudson,"  and  that  the  Shawangunk 
or  White  Mountain,  of  Ulster  and  Orange  counties,  forty  miles 
in  length,  "is  a  continuation  of  the  grit  and  rubble  of  the  First 


m 
I'-f 

W 


30  i:. 


SPECIAL    RKPOKT.      T.  STERRY  HUNT,  1875. 


graywackc  of  Rensselaer  county."  (Geological  Text  book, 
pages  74,  93,  123.) 

The  full  significance  of  these  observations  of  Eaton  was  not 
understood  til!  a  much  later  date,  as  will  appear  further  on. 

§  G2.  Next  to  Eaton  in  the  order  of  time  we  note  the  earlier 
publications  of  Henry  Darwin  Kogers.  The  geological  survey 
of  Pennsylvania  was  begun  by  him  in  1836,  and  was  actively 
carried  on  for  live  years,  or  until  1841.  In  his  fourth  i.nnual 
report,  tliat  of  1840,  we  find  a  detailed  ac  ount  of  the  for- 
mations of  the  south-eastern  part  of  the  state.  The  crystalline 
rocks  included  syenite,  serpentine,  etc.,  together  with  gneiss, 
mica-slate,  talc-slate,  and  "the  more  or  less  crystalline  lime- 
stones," of  the  Chester  and  Montg(jmery  valley,  lying  between 
the  Middle  and  Southern  gneissic  districts  and,  it  was  said, 
"obviously,  like  the  former  rocks,  belonging  to  a  Primary  date." 
While  all  these  rocks  were  thus  included  in  the  Primary  sys- 
tem, as  it  was  then  generally  understood,  the  limestones  of  tiie 
Lancaster  and  Kittatinny  valleys,  and  their  accompanying  sand- 
stones and  slates,  were  said  to  belong  to  the  Lower  Secondary 
or  Appalachian  series;  while  the  Mesozoic  sandstones  were 
called  Middle  Secondary.  The  next  annual  report,  in  1841, 
contains,  with  regard  to  the  Primary  scrip's,  only  a  few  points 
of  detail  ;  and  it  is  not  until  the  final  imblication  lA'  Rogers,  in 
1858,  that  we  find  his  later  views  with  regard  them,  as  set 
forth  in  the  preceding  chapter. 

§  63.  Simultaneously  with  the  work  of  Rogers  in  I'ennsyl- 
vania,  a  geological  survey  of  the  state  of  New  York,  begun  in 
1837,  was  in  [)iogre8s.  The  state  was  divided  into  four  dis- 
tricts, of  which  the  first,  or  southern,  wasc(jnfided  to  Prof.  \V. 
W.  Mather,  and  second  or  northern  to  Prof.  E.  Emmons.  The 
central  and  western  districts  were  entrusted  to  Messrs.  L.  Van- 
uxem  and  James  Hall ;  but  their  work  has  no  particular  bearing 
on  the  questions  now  before  us.  Messrs.  Mather  and  Emmons 
set  forth  their  views  on  the  geology  of  their  respective  region'^ 
in  various  annual  reports,  but  we  refer  for  a  full  ex[»osition  of 
them  to  their  final  reports,  of  which  that  of  Emmons  appeared 
in  1842,  and  that  of  Mather  in  1843. 

§  64.  Resting  upon  the  Primary  system  of  ancient  crystalline 
rocks,  in  northern  New  York,  there  were  found,  according  to 


THE    CHA.MPLAIN    DIVISION    OF    EMMONS. 


E.  31 


Emmons,  the  lower  members  of  the  New  York  Triinsition  sys- 
tem.    To  these  lower  members   Emmons,  as  is  well   known, 
gave  the  names,  in  ascending  order,  of  (1)  Potsdum  sandstone, 
(2)  Calciferous  sandrock,  (.3)  Cliazy  limestone,  (4)  Trenton  lime- 
stone, with  its  associated  sub-divisions  of  the  Birdseye  and  the 
Isle  La  Motte  or  Black  River  limestone,  (5)  Utica  slate,  (0)  Lo- 
raine  shales,  (7)  Cirey  sandstone,  (8)  Medina  sandstone.     These 
constituted,  according  to  him,  the  Champlain  division   of  the 
New  York  series.      The  Grey  sandstone,  which  in   Jetterson 
county  overlies  the  Loraine  shales,  was  l)y  him  regarded  as  the 
eciuivalent  of  the  conglomerate  of  Oneida.     This,  with  the  suc- 
ceeding Medina  sandstone,  has,  by  subsequent  geologists,  been 
separated  from  the  (Jhamplain  and  united  with  the  Ontario  di- 
vision; which  also  includes  the  Clinton  and  Niagara  tormations. 
§  G5.  To   the  Champlain  division,  also,    Emmons  referred 
certain  red  and  purple  slates  which,  tiiough   not   i'ound   in   the 
counties  to  the  westward,  constitute  a  narrow   belt   '*  which 
passes  through  the  higher  parts  of  Cohuubia,  Rensselaer  and 
Washington  counties,  and  onward  through  Vermont  into  Can- 
ada. It  is  every  wiiere  destitute  of  tossils."'  These  slates  were  sup- 
posed to  belong  to  the  J^oraine  formation,  while  to  the  succeed- 
ing sandstone  was  referred  the  so-called  Gray  wacke (the  Transi- 
tion graywacke  of  Eaton,)  which  forms  ranges  of  hills  in  the 
counties  just  named,  "and  alsooccui's  at  Quebec,"  It  is  described 
as  being  often  coarse  and  brecciated,  having  a  greenish  cement, 
supposed  to  be  derivi'd  from  "tlie  chloritic  slate  along  the  east- 
en\  boundary.''     To  this  horizon  was  also  referred  a  reddisii- 
brown    or   chocolate-colored    sandstone,    with    interlaminated 
red  shale,  stretching  along  the  eastern  border  of  Lake  Cham- 
plain,  and  to  the  west  of  the  Taconic  range,'"  in  Verniont.    Jie- 
sides  this  was  a  mass  of  limestone  immediately  succeeding  the 
red  sandstone,  traversed  with   numerous  veins  of  calcite  and 
quartz,  which  is  well  seen  in  Bald  Mountain,  and  is  the  Sparry 
limestone  of  Eaton.     This  rock,  according  to  Emmons,  extends 
tiirough  the  valley  of  l^ake  Champlain,  on   the  east  side,  and 
is  not  to  be  confounded  with  the  more  ancient  granular   lime- 
stone of  Berkshire  county.     All  of  the  rocks  mentioned  in  this 
section  were  said  to  be  without  fossils,  and  to  be  lithologically 
dissimilar  to  those  of  the  Champlain  division  as  seen  intheval- 


I 

i 


32  E. 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


■ 

i! 


I 


Iw 


I  III 


fr 


ley  of  the  Mohawk  and  west  of  the  Adiroudacks  ;  although  tliey 
were,  at  this  time,  unliesitatiiio;ly  referred  by  Emmons  to  the 
ui)[)er  portion  of  tliis  division  of  tlie  New  York  series.  (Ge- 
oloifv,  Second  district,  jiages  121-120). 

§  6t>,  The  rocks  to  whicli,  in  his  annual  reports  on  the  South- 
ern district,  Matlier  had  given  the  name  of  the  Hudson  River 
slates  or  shales,  were  by  Emmons,  in  1842,  regarded  as  a  south- 
ern prolongation  of  the  above  stratu  from  the  east  side  of  Lake 
Champlain.  The  name  of  Loraine  shales,  we  are  told  by  him, 
"is  simply  a  synonym  of  the  Hudson  River  shales,  both  terms 
being  occasionally  used  to  designate  the  same  rock.  They 
differ,  as  has  already  been  pointed  out,  only  in  the  physical 
changes  which  each  has  sustained.  At  Loraine  they  are  but 
slightly  removed  from  a  horizontal  [jositicm,  while  along  the 
Hudson  River  they  have  been  fractured  and  elevated  to  a  high 
angle,  or  a  steep  dip  to  the  east  has  been  given  them."  (Ibid, 
page  281.)  In  Vermont,  we  are  farther  told  that  the  Cham- 
plain  group  extends  for  six  miles  east  of  Ilighgate,  while  "at 
Slicldou  we  leave  the  Champlain  group  and  pass  directly  to  the 
Taconic  system,  consisting  at  its  extreme  north,  in  Vermont, 
of  the  same  masses  of  slate  and  limestone  as  in  the  counties  of 
Columbia  and  Dutchess  in  New  York.  Taking  a  general  view 
of  the  rocks  on  the  east  side  of  Lake  Champlain,  and  those  in 
the  same  range,  both  north  and  south,  we  find  them  consisting 
of  the  upper  members  of  the  Chami)lain  group.  To  the  east, 
succeeds  the  Taconic  system,  whose  width  is  from  six  to  twelve 
miles,  made  up  of  the  same  members  which  compose  it  in  Berk- 
shire county,  Massachusetts,  with  the  exception  of  the  granular 
quartz.  This  general  arrangement  extends  at  least  to  the  lati- 
tude of  Quebec,  presenting  one  of  the  longest  formations  yet 
known  to  geologists."     (Ibid,  page  322.) 

§  67.  The  Taconic  system,  as  at  this  time  defined,  included 
the  granular  quartz-nx^k  and  granular  limestone  of  the  Primi- 
tive series  of  Eaton  (T,  2  ;  I,  3,).  These  were  by  Emmons  sepa- 
rated from  the  rrimitive  schists  and  gneisses,  and  united  with 
the  Transition  argillite  (EI,  1)  to  form  what  he  regarded  as  a 
distinct  series;  which,  though  not  found  between  the  Primary 
and  the  New  York  series,  at  the  outcro])  of  the  latter  in  north- 
ern New  York,  was  sujiposed  to  be  intermediate  between  the 


f 


mathp:r  ox  new  york  geology. 


E.  3o 


two.  It  formed  tlie  Taconio  hills  of  western  New  England, 
occupying,  as  we  have  seen,  a  narrow  belt  between  the  Primary 
on  tbo  east,  and  the  disturbed  and  eastward-dipiiing  rocks,  re- 
ferred to  of  the  Cliamplain  division  of  the  Now  York  series,  on 
the  west;  tbo  boundary  between  which  and  the  Taconic  .system 
along  the  Hudson,  was  not  as  yot  distinctly  deiined  Ijy  Em- 
mons. The  rocks  of  these  two  series,  it  should  be  remembered, 
do  not  occur  within  the  limits  o*f  the  Northern  district  of  New 
York,  which  had  been  assigned  to  him. 

§  C8.  Mather,  in  his  final  rei  -rt  on  the  geology  of  the 
Southern  district  of  New  York,  which  appi»eared  in  1843,  or 
the  year  following  that  of  Emmons,  recognized  no  distinction 
between  the  New  York  series  and  the  Taconic  system,  which 
he  regarded  as  nothing  more  than  the  Champlain  division  of 
Emmons  (excluding  therefrom  the  Oneida  and  Medina  sand- 
stones,) in  a  modified  form.  The  granular  quartz-rock  of  the 
Taconic  was,  according  to  him,  the  Potsdam  ;  the  granular  lime- 
stone was  the  Calciferous  «androck,  with  the  succeeding  Chazy 
and  Trenton  formations  ;  while  the  Hudson  River  Argillite  se- 
ries, including  the  roofing-slates,  represented  the  Utica  slates 
and  the  Loraine  shales. 

§  69.  The  district  examined  by  Mather  included  the  Hudson 
valley  from  the  crystalline  Primary  rocks  of  Washington  and 
Saratoga  counties  on  the  north  to  the  similar  crystalline  rocks 
of  the  Highlands  on  the  south.  He  pointed  out  what  he  .called 
the  Hudson  axis,  extending  from  Baker's  Fal»  on  the  Hud- 
son river,  near  Sandy  Hill  in  Washington  county,  southward 
by  Saratogsi  Lake,  Glen's  Falls,  New  Baltimore,  Catskill  and 
Kingston.  This  axis  "may  be  traced  farther  to  the  south  in 
the  Comfort  liills  of  Orange  county,  between  the  Wallkill  and 
the  Shawangunk  rivers,  and  is  probably  an  extension  of  that  of 
Pochunk  Mountain,  on  the  New  Jersey  line."  It  thus  skirts 
the  Hudson  river  for  more  than  one  hundred  miles.  (Geology, 
First  district,  pp.  357,  375,  623.) 

§  70.  The  course  thus  defined,  which  is  declared  to  bo  "a  line 

of  fracture,  and  an  anticlinal  axis,"  is  indicated  with  more  pre- 

cisenoss  of  detail  in  the  Fifth  annual  report  of  Mather,  (page 

66,)  where,  in  its  northward  extension  from  Orange  county,  it 

3— E. 


m 


T 


34  E. 


SPECIAL   REPORT.      T.  STEKRY    HUNT,  1875. 


i-i 

HI 


is  said  that  it  ''crosses  the  tShawaiiguiik  Mountains  with  a  very 
acute  angle,  [)as8eH  near  Kingston,  thence  halt'  a  mile  east  of 
the  i'all  of  Esopus  creek,  hy  vSaugerties,  alung  the  ridge  hetween 
Catskill  village  and  the  Katei*skill  creek  on  the  road  to  the 
Mountain  JJou.se  ;  near  Madison,  three  miles  north-west  of  Cats- 
kill;  four  miles  west  of  Athens;  three  miles  we*;t  of  Cox- 
sackie,  and  ahout  the  same  distance  west  of  ^'ew  Baltimore  and 
Coeymans.  Its  continuation  in  Alhany  county  is  seen  whore 
the  Normanskill  and  Mohawk  intersect  it.  It  crosses  the  Mo- 
hawk a  few  miles  helow  the  aqueduct,  and  ranges  thence,  hy 
!Saratoga  Lake,  to  Baker's  Falls  on  the  Hudson."  To  the  east 
of  this  line  the  strata  present  characters  very  unlike  those  on 
the  west. 

§  71.  This  line  corresponds  to  that  defined  by  Eaton  between 
the  Transition  Argillite  and  the  uucontbrmably  overlying  Tran- 
sition Graywacke,  a  fact  which  serves  to  explain  the  language 
of  Mather,  who  informs  us  that  "the  horizontal  and  slightly  in- 
clined slates  and  grits  of  the  Hudson  River  group  lying  to  the 
west  of  tills  axis  *  *  '^  were  formerly  considered  as  more 
recent  strata  than  the  upturned  rocks  of  the  Hudson  River  val- 
ley, and  as  resting  unconlbrmably  upon  them."  Me,  however, 
maintained  and  sought  to  prove  the  identity  of  the  rocks  in 
the  two  regions,  though  he  declared  that  "the  upturned  rocks 
are  so  much  modified  in  their  characters  by  the  causes  which 
have  deranged  their  position,  that  it  requires  the  strongest  evi- 
dence to  convince  one  that  they  are  no  older  than  the  horizon- 
tal rocks  west  of  the  axis  of  disturbance."  In  proof  of  this 
view  he  aflirmod  that  it  was  possible  in  many  cases  "to  trace 
the  strata  across  the  axis  of  disturbance,"  and,  moreover,  to 
lind,  in  various  localities  among  the  disturbed  rocks,  fossils  of 
the  Champlain  division,  especially  the  graptolites  of  the  Utica 
slates. 

§  72.  The  strata  of  this  disturbed  region  dip  constantly  to  the 
eastward,  and  often  at  angles  ap)  iroach  ing  the  vertical.  They  are 
also,  according  to  Matlier,  affected  by  numerous  fractures  and 
faults,  which  "  have  deranged  all  the  rocks  of  the  Champlain 
division  and  packed  them  together  '•  *  in  the  utmost  con- 
fusion." "  Thev  are  contorted,  broken  and  wrinkled  in  almost 
every  conceivable  manner,"  and  "  the  repetitions  of  the  same 


> 


'J 


MATHER   ON    NEW    YORK    GEOLOGY. 


E.  35 


strata  with  others  lying  lower  and  higher  in  the  geological  series, 
and  with  frequent  apparent  inversions  in  the  order  of  superpo- 
sition, render  it  almost  impossihle  to  determine,  from  an  exam- 
ination of  the  strata  on  the  east  bauii  of  the  Hudson,  what  the 
real  order  of  superjiosition  is.  Other  difficulties  also  present 
themselves,  viz:  the  fossiliferous  rooks  dip  to  the  east,  and  a|>- 
[•arently  plunge  under  those  which  have  been  considered  of 
more  ancient  formation  ;  and,  on  the  eastern  Hank  of  the  Hud- 
son valley,  these  plunge  apparently  under  what  we  have  been 
accustomed  to  consider  very  ancient  rocks,  as  gneiss,  granite, 
mica-slate,  etc."  That  these  disturbed  strata,  destitute  of  fos- 
sils, often  with  glazed  surtaces,  more  or  less  talcose  in  aspect, 
traversed  in  parts  by  numerous  quartz  veins,  and  including 
many  "anomalous  rocks,"  were  very  unlike  the  Champlain  di- 
vision as  seen  in  the  Northern  district,  to  the  south  and  west  of 
the  Adiroudacks,  was  thus  clearly  recognized  by  Mather,  who 
nevertheless  believed  the  two  to  be  equivalents  in  geological 
j)osition. 

§  73.  We  have  next  to  notice  belts  of  rocks  in  this  region, 
referred  by  Mather  to  the  Ontario  division  of  the  New  York 
series.  First  of  these,  on  the  west  side  of  the  Hudson,  is  the 
!Shawany;unk  range,  extending  from  the  New  Jersey  line  north- 
eastward  a  dist  lUce  of  *bity-three  miles  to  Ivoscidale,  near 
Kingston,  and  regarded  as  a  prolongation  of  the  Kittatinny 
range  of  Pennsylvania.  The  strata  of  this  range  are  chietly  of 
sandstone  and  conglomerate,  gray  or  white,  and  more  rarely  red, 
with  slaty  layers.  They  are  described  as  resting  unconfurmably 
upon  the  Hudson  Hiver  slates,  and  as  contormably  overlaid  by  red 
slates  and  marls,  regarded  as  re[)resentiiig  the  Medina  ;  tlie  sand- 
Htone  itself  being  su[»posed  to  be  the  eciuivalent  of  the  (Jneidu. 
The  dip  of  this  lormation  is  to  the  north-west,  sometimes  at  a 
high  angle.  It  is  remarkable  for  its  quartz  veins  carrying  sul- 
pliuivttetl  ores  ol'  lead,  copperaiid  zinc;  and  for  its  beds  of  ct)n- 
glomerate,  in  which  the  cemeni  is  pyrites,  ench)sing  pebbles 
and  grains  of  quartz. 

§  74.  Besides  this  range,  Mather  noticed  to  the  south-east 
another  conqtosed  of  somewhat  similar  rocks,  which  are  traced 
at  intervals  from  the  New  Jersey  line,  by  the  west  of  Long 
J'ond,  north-northeast   to  near  Canterbury  in  Cornwall,  Or- 


36  E. 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


?r 


ange  county.  Tlieae  were  regarded  by  Mather,  and  by  Rogers, 
as  the  extension  of  the  Green-Pond  Mountain  range  of  New- 
Jersey  ;  and  were  supposed  by  the  latter  to  be  of  the  age  of  the 
Mesozoic  sandstones  whicli  are  found  to  the  south-cast  of  them. 
Mather,  however,  considered  them  as  the  geok)gical  equivalents 
of  the  8hawangunk  range,  which  they  resemble  lithologically ; 
and  described  the  occurrence  of  shales  with  organic  re- 
mains of  Lower  Ilelderberg  age,  associated  with  the  con- 
o;lomerate  of  this  series,  at  Townsend's  iron  mine  in  Cornwall. 
These  sandstones,  conglomerates  and  shales  are  well  displayed 
in  I'ine  Hill  and  Blooming  Grove,  and  in  Belvaie  and  Skunne- 
munk  Mountains,  in  Orange  county. 

§  75.  The  important  fact  connected  with  this  series  of  rocks 
is  that,  according  to  Mather,  similar  rocks,  consisting  of  coarse 
white,  gray  and  greenish  sandstones,  red  and  white  conglom- 
erates and  red  shales,  '"are  found  on  the  east  side  of  the  Hud- 
son valley,  ranging  from  Fishkill,  near  Matteawan,  through 
Dutchess,  Columbia,  Rensselaer  and  Washington  counties  into 
Vermont,  in  West  Poulteney ;  a  distance  of  more  than  200  miles 
from  their  southern  terminatioti  in  New  Jersey."  These  rocks 
frequently  occupy  two  or  three  parallel  belts  one  or  two  miles 
apart,  and  are  often  associsited  with  limestone  in  Orange  county, 
as  well  as  in  the  counties  east  of  the  Hudson  River;  where  they 
rest  on  the  Argillites  ot  the  Hudson  River  group,  and  dip  to 
high  angles  to  the  eastward  ;  while  in  the  Highlands  they  are  in 
contact  witli  the  Primitive  gneiss,  and  have  a  similar  inclina- 
tion, or  are  even  vertical  in  attitude.  In  many  instances  no- 
ticed by  Horton  (the  assistant  of  Mather)  in  Warwick  and 
Munroe,  Orange  county,  where  this  sandstone  formation  (Gray- 
wacke)  occurs  on  the  northwest  side  of  the  gneissic  hills,  "the 
lines  of  bearing  and  dip  of  the  Graywacke  coincide  with  those 
of  the  Primitive,  and  the  Graywacke  has  the  appearance  of 
passing  beneath  the  Primitive  rock.  At  the  western  base  of 
Goosopond  Mountain,  and  of  Sugar  Loaf  Mate,  the  slate  has  the 
same  jiosition  in  reference  to  the  Primitive,  and  exhibit«  pre- 
cisely the  same  appearance." 

§  76.  The  conclusions  of  Horton    from   the  study  of  these 
rocks,  chiefly  in  Orange  county,  may  be  thus  summed  up: 

1°.  The  slate  (Argillite)  and  the  Graywacke  of  the  Hudson 


IIORTON    ON    NEW    YORK    GEOLOGY. 


E.  37 


River  are  iiiterstratilied  with  each  other,  forming  a  coiitenipo 
raneous  series  (A) ;  and  the  limestone  of  Neeleytown  and  the 
hlue  limestones  of  Nevvburg,  Munroe,  Blooming  Grove  and  Go- 
shen are  interstratilied  with  this  series. 

2°.  Tliegrit  ot  Shawangunk  Mountain  (B)  rests  unconforma- 
bly  upon  the  basset  edges  of  the  Argillite  and  Graywacke  se- 
ries. 

2°.  The  grit  and  Graywacke  of  Pine  Hill,  Blooming  Grove, 
Bolvalo  and  Skunneinui»k  Mountains  (C)  also  rest  on  the  same 
Argillite  and  Graywacke  series  (A);  whether  unconformably  is 
not  stated. 

4°.  The  "conglomerate  and  fossiliforous  limestone  of  Go- 
shen" (D)  are  newer  than  the  blue  limestones  mentioned  above, 
since,  like  the  rocks  C,  they  rest  upon  the  series  A. 

5°.  The  limestone  at  the  foot  i>f  Shawangunk  Mountain 
rests  conformably  on  the  Shawangunk  grit,  and  is  overlaid  by 
the  Graywacke  of  Deer  Park,  (the  sandstones  of  the  Devon iaii 
series.     (Geology,  First  district,  page  580). 

These  interrupted  belts  of  sandstones,  conglomerates  and  red 
shales,  (the  grit  and  graywacke,)  are  traced,  according  to 
Mather,  from  New  Jersey  to  Vermont;  and  although  their 
identity  with  the  Shawangunk  range  was  not  certain,  they  were 
by  him  referred,  like  it,  to  the  Ontario  division  of  the  New- 
York  series,     (ibid,  pages  362-365). 

§  77.  Emmons,  as  we  have  seen,  did  not,  in  1842,  clearly  de- 
line  the  limits  between  the  Taconic  system  and  the  rocks,  re- 
garded as  belonging  to  the  Chaniplain  division,  which  bounded 
it  on  the  west;  the  position  of  the  two  giving  rise,  according 
to  liim,  to  "many  doul)T8  and  perplexities  as  regards  the  true 
limits  of  either  system."  Far  from  including  in  the  Taconic 
system  the  whole  of  the  highly  disturbed  region  along  the 
Jludson  valley,  ibis  system  was,  at  that  time,  confined  to  a  nar- 
row belt  along  the  western  border  of  the  Primary,  while  the 
strata  between  this  belt  and  the  river  were  still  included  by 
Enmions  in  the  Champlain  division. 

§  77A.  According  to  Mather,  the  rocks  of  the  Taconic  system, 
as  thus  limited,  have  tiie  same  dip  and  strike  as  the  rocks  of 
the  Champlain  division,  "and  apparently  overlie  theni ;"  the 
di])  of  the  strata  being  easterly,  and  at  angles  of  from  30°  to 


38  E. 


SPECIAL   REPORT.      T.  STERRY  HUNT,  1875. 


I 


\^ 


90°.  "Although  the  rocks  ull  dip  in  the  same  general  direction, 
similar  strata,  at  no  great  distances,  are  frequently  reverseJ  in 
the  relative  order  of  their  supposition."  It  was  iinp()S3ible  to 
draw  any  line  of  deniarkation  between  the  r:)cks  of  the  Ta- 
conic  system  and  those  of  the  so-called  Champlain  division,  in 
this  region,  and  Mather  was  forced  to  the  conclusion  that  they 
belong  to  one  and  the  same  series.  In  his  own  words,  ho  con- 
ceived that  "  the  Taconic  rocks  are  the  same  in  age  with  those 
of  the  Champlain,  but  modilied  by  metamoridiic  agency  and 
by  the  intrusion  of  plutouic  rocks."  (Geology  First  district, 
page  438). 

§  78.  Similar  conclusions  were  reached  by  11.  D.  and  W.  13. 
Rogers,  as  the  result  of  sections  made  across  portions  of  the  re- 
gion in  question,  and  set  forth  in  a  communication  to  the  Ameri- 
can I'hilosophical  Society  in  1841;  in  which  they  asserted  that 
the  Taconic  rocks  were  identical  with  those  of  the  Hudson 
valley,  and  referred  both  to  the  Champlain  division  of  the 
New  York  series.  They  declare  that  where  "  the  exact  order 
of  superposition  of  these  rocks  and  the  Primary  can  be  ex- 
amined, it  is  found  ;  first,  that  the  granular  quartz  either  rests 
upon  or  pitclies  immediately  under  the  gneiss  or  granitic  rocks  ; 
second,  that  the  limestones  lie  next  in  order  from  the  gneiss  or 
granite,  either  in  super  or  sub-position ;  and,  third,  that  the 
slates  next  follow."     (Ibid,  page  423). 

§  79.  Before  proceeding  further  in  the  description  of  the 
Taconic  rocks,  we  may  notice  the  views  of  Mather  and  Em- 
j  mons,  and  of  some  others  who  had  preceded  them,  regarding 
•  the  crystalline  formations,  which  are  found  north,  east  and 
south  oT  these,  in  the  state  of  New  York.  These  crystalline 
rocks  were  described  by  Mather  under  two  heads,  the  Primary 
and  the  Metamorphic  divisions.  To  the  former  were  referred 
the  granitoid,  gneissic  and  hornblendic  rocks  of  the  Highland 
chain,  found  in  Putnam,  Westcliester,  Dutchess,  Rockland  and 
Orange  counties ;  with  which  were  also  classed  the  similar 
rocks  of  Saratoga  and  Washington  counties,  included  within 
the  northern  part  of  the  First  district.  The  rocks  of  this 
range,  as  is  well  known,  are  continued,  with  the  same  lithologi- 
cal  characters,  in  the  South  Mountain  range  into  Pennsylvania; 
where  they  constitute  the  Northern  and   Middle    gneissic  dis 


MATHER  ri    FlUST    METAMORPIIIC    (JUOUP. 


E.  39 


tricts  of  Rogers  (§  12).  No  attempt  was  made  on  the  geologi- 
cal map  of  New  York  to  trace  the  limit  between  these  Primary 
rocks  and  the  succeeding  Metaniorphic  series. 

§  80.  Tiie  n)cks  to  whicli  he  gave  the  name  of  Metamorphio 
were  divided  by  Mather  into  two  groups.  Of  these  the  tirst 
and  most  important  is  that  series  described  by  Emmons  as  tlie 
Primary  belt,  bounding  on  the  east  the  Taconic  range  in  Ver- 
mont and  western  Massachusetts.  It  enters  the  state  of  New 
York,aci  ording  to  Mather,  in  the  northeast  corner  of  Dutchess 
county,  extending  thence  along  the  southea3tern  side  of  the 
Highland  range  to  the  Hudson,  and  to  Long  Island,  and  in- 
cluding the  county  and  city  of  New  York.  The  rocks  of  this 
belt  are  described,  to  the  north  of  the  Highlands,  as  chietiy  mi- 
caceous, talcose  and  cbloritie  slates,  with  quartzites  and  more 
or  less  crystalline  limestones  or  dolomites;  while  south  and  east 
of  the  Highlands,  in  Westchester  and  New  York  counties,  are 
found  still  more  crystalline  limestones,  associated  with  mica- 
schists,  micaceous  gneiss,  hornblendic  rocks,  granite,  syenite 
and  serpentine;  the  latter  three  being  regarded  as  plutonic 
rocks.  In  this  Metamorphic  series  are  included,  as  will  be 
seen,  the  limestones,  mica-schists  and  gneisses  of  Manhattan 
island,  as  well  as  the  belt  of  steatite  and  anthophyllite-rock, 
with  serpentine,  found  on  the  western  side  of  the  city  of  New 
York;  which  is  apparently  related  to  the  similar  rocks  of 
IIol)oken  and  Sfaten  Island.  At  Stony  Point,  on  the  Hudson, 
tliehornbIen<lic  rocks  are  said  to  be  traversed  by  parallel  dykes 
of  serpentine  and  of  greenstone,  the  latter  being  penetrated 
by  magnesian  minerals  like  those  of  Hoboken.  Another  simi- 
lar belt,  with  serpentine,  is  found  near  New  Rochelle. 

§  81.  The  Taconic  rocks  pass  to  the  west  of  the  Hudson,  innne- 
diatel_)  north  of  the  Highland  range,  which,  for  a  considerable 
distance  to  the  north-east,  divides  them  from  the  Metamorphio 
belt,  but  where  this  sepai-nting  range  disappears,  and  the  Ta- 
conic and  Metaranrj)hic  rocks  come  in  contact,  "no  well  marked 
line  of  distinction  can  be  drawn,  as  they  blend  into  each  other 
])y  insensible  shades  of  difference."  The  diliieulty  of  deter- 
mining the  relations  of  these  rocks  is  rendered  greater  by  the 
fact  that  the  whole  series  dips  to  the  eastward,  generally  at  a 
high  angle,  so  that  the  newer  seem  to  pass  below  the  older,  and 


m 


40  E. 


SPECIAL   REPORT.      T.  8TERRY    HUNT,  1876. 


these,  in  their  turn,  plunge,  apparently,  beneath  the  j^raniticand 
gneissic  and  micaceoua  rocks  which  lie  to  the  eastward  of  thera. 
(See  the  words  already  quoted,  §  72.)  The  final  conclusion  of 
Mather  was  that  the  rocks  of  this  Metaniorphic  belt,  (in  which 
he  ineluded,  moreover,  all  of  the  crystalline  rocks  of  western 
New  England)  were  nothing  more  than  the  Ir'otsdam  sand- 
stone, the  Calciferous  sandstone  and  the  Trenton  (Mohawk) 
limestones,  together  with  the  slate  rocks  of  the  Hudson  val- 
ley, in  an  altered  condition;  "that  Ihey  were,  in  fact,  the  rocks 
of  the  Champlain  division,  but  much  more  altered  and  modi- 
fied by  metamorphic  agency  than  the  Tacouic  rocks,"  which 
he  calls  "imperfect  Metamorphic  rocks."  Elsewhere  he  con- 
cludes that  "the  limestones,  at  least,  and  probably  the  asso- 
ciated micaceous  gneiss,  mica-slate,  hornblende-slate  and  horn- 
blende rocks,  are  Metamorphic  rocks,  more  recent  in  their 
change  than  the  Taconic  rocks.  In  fact  they  are  notbing  more 
than  the  rocks  of  the  Champlain  division,  modified  greatly  by 
metamoriihic  agency,  and  by  the  intrusion  of  granitic  and 
trappean  aggregates."  (Report  of  First  district,  pages  464, 
626,  628.)  ^ 

§  82.  Further  on,  he  expresses  the  opinion  that  many  of  the 
rocks  called  by  him  Primary,  including  even  certain  of  the 
gneisses,  may  perhaps  be  of  the  same  age  as  the  Metamorphic 
rocks.  This  view  was  extended  to  what,  by  himself  and  others, 
had  been  called  the  Primary  limestone  of  the  Highlands,  and 
which,  in  bis  report  of  the  First  district,  makes  a  second  group 
of  Metamorphic  rocks.  The  crystalline  limestones  of  this 
group  are,  according  to  Mather,  mineralogically  very  distinct 
from  those  of  the  preceding  division,  and  are  characterized  by 
containing  grajjhite,  serpentine,  chondrodite,  hornblende,  py- 
roxene, magnesian  mica,  scapolite,  apatite,  spinel,  sphene,  and 
many  other  crystalline  mineral  species.  As  described  by  ilor- 
ton,  the  assistant  of  Mather,  the  limestone  is  said  to  be  "inter- 
stratified  with  the  granitic  and  hornblendic  rocks,"  and  again, 
"in  contact  with  the  granite,  the  gneiss  and  hornblende  rocks  • 
sometimes  between  them,  sometimes  al)ove  them,  and  sometimes 
beneath  them.  It  is  not  stratified."  (Ibid,  page  677.)  The 
conclusion  adopted  by  Mather,  from  a  survey  of  these  rocks  in 
the  Highlands,  in  Orange  county.  New  York,  and  Sussex  county, 


MATHER  S  SECOND  META.MUIU'IIIC  GROUP. 


K  41 


New  Jersey,  is  that  the  crystjilliiie  limestones,  which  are  lurirely 
disphiyed  in  this  rej^ion,  together  with  their  iissociuted  <rrunitic 
and  liornblendic  aggregates,  are  notiiing  more  than  moditioa- 
tions  of  the  Potsdam  sandstone  and  the  aecomiianying  fossil- 
it'erous  limestones  of  tlie  Chami)lain  division.  In  tiie  War- 
wick valley,  he  tells  us,  "the  limestones  can  be  easily  traced 
through  all  the  changes  from  a  fossiliferous  to  a  crystalline 
white  limestone,  containing  crystallized  minerals  and  plum- 
bago;" and  he  extends  the  same  view  to  the  similar  limestones 
with  the  y-neissic  rocks  of  Saratoo;a  and  WashiniJ-ton  counties. 
(Ibid,  pages  465,  476,  486.)  From  the  interstratification  of 
these  crystalline  limestones  with  gneissic  and  hornblendic 
rocks,  he  was  thus  forced  to  admit  the  paleozoic  age  of  these 
latter,  and  hence  the  doubt  which,  as  we  have  seen,  was  thrown 
by  liim  upon  the  age  of  certain  of  the  gneissic  rocks  previously 
designated  as  Primary. 

§  88.  To  tlie  student  of  geology,  who  is  aware  of  its  now 
universally  admitted  fallacy,  it  is  no  small  interest  to  trace  the 
history  of  this  view  of  metamorphism,  as  applied  to  tiie  rocks 
in  question.  Nuttall,  who  is  believed  by  Mather  to  have  first 
enunciated  it,  says,  in  1822,  (American  Journal  of  Science, 
[I]  vol.  V,  page  267,)  in  describing  these  limestones  iu  Frank- 
lin, Sussex  county,  New  Jersey :  "  The  crystalline  calcareous 
rock,  which  here  alternates  with  grani tines  of  feldspar  and 
quartz,  or  with  beds  of  syenitic  granite,  disappears,  and  a  con- 
fluent gray wacke, almost  por{)hyritic,  and  contemporaneous, ap- 
parently, with  the  other  formations,  appears  directly  overlaid  by 
a  bed  of  leaden,  minutely  granular  secondary  limestone,  con- 
taining organic  remains  of  the  usual  shells  and  corallines,  and 
layers  of  blackish  hornstone."  These  rocks  were  farther  de- 
scribed as  passing  into  each  other,  the  gray  wacke  imiiercepti- 
bly  blending  with  the  granitic  and  syenitic  rocks  of  the  High- 
lands. 

§  84.  These  views  were  adojfted  by  II.  I).  Rogers,  so  far  as 
regards  the  crystalline  limestones  of  the  Highlands  of  New 
Jersey,  and  are  set  forth  with  great  fullness  by  him  in  his  final 
report  on  the  geology  of  that  state,  in  1840,  which  is  quoted  by 
Mather.  lie  however  made  an  important  ad<lition  to  the  hy- 
pothesis, for  while  Mather  was  content,  in  a  general  way,  to 


ft 


m 


42  E. 


SPECIAI,    IlEI'OKT.       T.  STKRRY    HUNT,  1875. 


W'- 


imaf^iiie  that  heiit  had  etrectod  tlie  supposed  chanpjes  in  the 
paU'ozoic  sediments,  Rogers  endeavored  to  siiow  that  eruptive 
or  plufonic  rocks  ha<l  i)een  the  source  of  the  lieat  which  iiad 
altered  the  f'ossiliferous  limestones.  We  have  already  noted 
the  extreme  length  to  which  he  (tarried  liis  plutonic  views, 
(§  39,)  and  it  will  he  found  that  he  is  not  at  a  loss  for  igneous 
rocks.  The  well-known  interstratified  deposit  of  franklinite, 
with  oxide  and  silicate  of  zinc,  in  Franklin  and  Sterling,  New 
Jersey, is,  according  to  Rogers,  an  "intrusive  vein,"  injected 
hetwen  tlie  gneiss  and  the  overlying  Transition  limestone, 
wliicli,  hy  the  action  of  "the  intensely  heated  metalliferous 
vein,"  has  heen  changed  into  a  sj)arry  calcareous  rock,  filled 
with  crystallized  minerals.  In  another  locality  in  tlie  High- 
hauls  he  lias  descrihed  "a  granitic  dyke  or  vein"  consisting 
of  quartz,  carhonate  of  lime,  feldspar,  augite  and  mica,  with 
sj)inel  and  sapi)hire.  This  is  called  a  "vein  of  igneous  mat- 
ter," which,  having  been  itself  in  a  melted  condition,  is  sup- 
jiosed  to  have  fused  the  limestone  with  which  it  came  in  con- 
tact; the  two  rocks  becoming  so  mingled  that  no  line  of  dc- 
markation  between  is  now  visible.  According  to  him,  there 
him,  tliere  can  be  seen,  in  certain  localities,  a  gradation  from 
the  crystalline  graphitic  limestone  to  the  blue  and  earthy  lime- 
stones, which  he  suhse(iuently  named  the  Auroral.  Notwith- 
standing that  the  dip  of  these  limestones  was  here  generally  to 
the  north-west,  at  moderate  angles,  while  the  crystalline  sparry 
limestone,  like  the  accompanying  gneiss,  liad  a  steep  dip  in  the 
op})osite  direction,  Rogers  was  able  to  find  a  section  in  which 
these  latter  rocks  had  a  dip  aj)parently  coniormable  with  the 
blue  limestone  and  the  Primal  sandstone,  thus  supporting  his 
view  that  the  whole  belonged  to  one  series.  It  may  here  be  re- 
marked that  some  portions  of  the  ancient  limestones  of  the 
gneissic  series  are  fine-grained  and  bluish  in  color,  so  that  thev 
resemble  not  a  little  the  more  crystalline  beds  of  the  Auro' 
Tliis  was  the  only  fact  underlying  the  assumption  of 
morphic  origin  and  the  paleozoic  age  of  the  crystii  liun 

Btones  of  the  Highlands,  a  notion  which  the  labors  >!  Prof. 
Cook  and  his  associates  of  the  i)rcsent  geological  survey  I" 
New  .Jei*sey  have  shown  to  be  a  fallacy,  as  those  of  Emmons  in 
northern  New  York,  and  of  the  geological  survey  of  Canada, 
hnw  long  sinci"  di'inonstrated  for  the  latter  regions. 


1^ 


EMMONS  ON  THK   IMlIMAUY   ROCKS. 


E.  4;; 


§  85.  While  he  adopted  to  a  very  threat  extent  the  views  of 
Niittall  and  of  J-i()i,'ers,  .Nhitlier  (lid  not  i\\>\>]\  them  to  all  the 
crystalline  liniestonea.  He  refers  to  the  view  of  Emmons  that 
crystalline  limestone  is  an  eruptive  rock,  and  says  tliat  there 
are  many  examples  in  the  J'limary  rei;ions  of  \Vashiii<;ton 
county  which  serve  to  demonstrate  this,  and  leave  little  or  iio 
douht  that  the  rock  was  "  injected  in  a  fluid  state."  In  another 
locality,  a  cliit'of  white  crystalline  limestone  is  said  to  include 
"a  mass  of  stratified  hornhlendic  giu'iss distinctly  imhedded  in 
it."     (Geoloiry,  First  district,  page  485.) 

§  86.  Emmons,  in  his  final  rejjort  on  the  Northern  district 
of  Xew  York,  in  1842,  (U'scrihed  as  I'rimary  rhe  crystalline  rocks 
of  the  Macomb  Mountains ;  to  which  region  the  name  of  the 
Adirondacks, at  first  applied  to  their  highest  group  of  liills,  has 
since  been  extended.  It  embraces  the  crystalline  rocks  of 
Washington  and  Saratoga  counties,  which  were  included  in  the 
Southern  district  and  noticed  by  Mather.  The  crystalline  rocks 
of  this  great  Primary  region  were,  by  Emmons,  divided  into  two 
principal  groups:  1st,  Unst  rati  tied;  including  granite,  hyper- 
stliciie  rock,  crystalline  limestone,  serpentine  and  rensselaerite  ; 
'2(1,  Stratified  ;  embracing  gneiss,  hornblende-rock,  syenite  and 
steatite.  In  a  subordinate  group  were  included  certain  {)or- 
phyry  and  traps  traversing  the  rocks  of  the  New  York  series, 
(which,  in  parts  of  the  regic»n,  overlie  the  Primary)  and  the  mag- 
netic and  specular  oxides  of  iron,  found  in  the  gneissic  and  hy- 
persthenic masses,  and,  like  the  1st  group,  regarded  as  unstrati- 
fied.  Granite,  according  to  him,  was  rare,  and  was  so  often 
found  i>assiug  into  gneiss  that  he  regarded  the  distinction  be- 
tween the  two  rocks  as  an  unimportant  one,  and  declared  that 
it  was  in  many  cases  impossible  to  determine  whether  a  given 
r(jck  belonged  to  the  one  or  the  other  of  these. 

§  87.  It  should  here  be  noted  that  Emmons  did  not  accept  the 
so-called  metamorphic  theory  of  crystalline  rocks,  adopted  by 
Nuttall,  Rogers  and  Mather,  which  maintains  gneiss  to  be  the 
result  of  an  alteration  of  uncrystalline  sedimentary  matters,  of 
which  process  granite  is  only  the  last  term.  The  view  held  by 
Emmons  still  finds  favor  with  a  considerable  school  of  geolo- 
gists, according  to  whom  the  stratified  crystalline  rocks  are  of 
igneous  origin,  and  owe  their  banded  structure  to  an  arrange- 


44  E. 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


merit  of  their  mineral  constituents  by  movements  while  yet  in  a 
liquid  state,  so  that  gneiss  may  be  deliiied  as  a  laminated  gran- 
ite. These  stratified  rocks,  which  Enmions  designated  by  the 
term  Fyrocrystalline,  were  regarded  as  igneous,  and  in  no  sense 
of  sedimentary  origin.  Tlie  associations  of  the  crystalline  lime- 
stones with  tlie  granitic  and  gneissic  rocks  were  such  that  these 
too  were  regarded  as  of  igneous  origin  ;  a  view  which  he  main- 
tained at  length,  in  opposition  to  the  theory  of  their  sedimentary 
nature  supported  by  Hitchcock,  Rogers  and  Mather.  The 
same  view  was  by  him  extended  to  the  serpentine  and  renssel- 
aerite,  so  oft^n  associated  with  these  limestones.  The  igneous 
nature  of  crystalline  or  primary  limestone  was  at  that  time 
taught  by  many  European  geologists  of  distinction,  and  a  simi- 
lar view  ci  the  nature  of  serpentine  is  still  prevalent. 

§  88.  The  name  of  hypersthene-rock,  (previously  applied  to 
a  similar  aggregate  in  the  Western  Islands  of  Scotland,  by  Ma- 
cuUoch,)  was  given  by  Emmons  to  a  formation  which  occupies 
the  greater  part  of  Essex  county,  New  York,  i'orming  the 
highesthills  in  the  district.  It  was  correctly  described  by  him 
as  consisting  chietiy  of  labradorite,  fref|uently  intermixed  witii 
hyperstheue  ;  while  certain  varieties  of  the  rock  contained  also 
hornblende,  epidote,  mica  and  garnet.  An  unstratified  rock  like 
granite,  it  was,  like  it,  declared  to  be  intermixed  with  and  pene- 
trated by  crystalline  primary  limestone,  marked,  as  elsewhere 
in  the  Adirondack  region,  and  in  the  Primary  rocks  of  the  High- 
lands, in  the  Southern  district,  by  pyroxene,  hornblende,  scapo- 
lite  and  apatite.    (Geology, Second  district,  pages  89,40), 

§  89.  We  have  already  set  forth  the  views  of  Emmons  re- 
garding the  Taconic  and  New  York  systems,  as  taught  by  him 
in  18-42.  In  184G,  aitpearcd  his  volume  on  the  "Agriculture of 
New  York,"  in  which,  while  giving  a  summary  of  the  geology 
of  the  whole  siate,  he  revised  his  opinions  on  the  Taconic  and 
the  Chaniplain  rocks.  The  former  were,  in  1842,  restricted  to  a 
narrow  belt  between  the  Primary  rocks  on  the  east  and  the 
New  York  series  on  the  west;  this  position  giving  rise,  in  the 
language  of  Emmons,  "to  many  doubts  and  peri)lexities  as  re- 
gards tlie  true  limits  of  either  system."  The  disturbed  strata 
on  the  east  side  of  the  Hudson,  thus  referred  by  Emmons  to 
the   Utica  and   Ijoraine  formations,  could   not,  according  to 


EMMONS   ON    THE    TACONIC    SYSTEM. 


E.  45 


Matlier,  be  separated  from  tlie  Taeonic,  wliicli  he  tlierefore  re- 
garded as  one  with  theChumplain  division.  In  184tJ,  Emmons 
himself  recognized  this  identity,  but  extended  to  the  whole  the 
name  of  Taeonic.  He  explained  that  he  had,  in  1842,  referred 
the  Taeonic  roofing-slates  to  the  ujiper  [Kirt  of  the  Champlain 
division  on  account  of  some  markings  on  tliem,  whi<h  were 
mistaken  for  the  graptolites  of  tlie  Utioa  formation. 

§  90.  There  remained,  however,  this  important  ditierenco  be- 
tween Mather  and  11.  D.  Kogers,  on  the  one  hand,  and  Em- 
mons on  the  other,  that  while  the  former  geologists  maintained 
■"hat  the  whole  of  the  disturbed  strata  in  question  belong  to 
the  Champlain  division,  the  latter  asserted  tliat  tliey  consti- 
tute an  older  series,  upon  which  the  different  members  of  this 
division  rest  unconformably.  He  had  previously  declared 
the  Taeonic  system  to  be  "  equivalent  to  the  Lower  (.'anibrian 
of  Prof.  Sedgwick,"  (Geology,  Second  District,  page  103,)  and  he 
now  asserted  that  "  the  Taeonic  s  stem  occupies  a  position  in- 
ferior to  the  Champlain  division  of  the  New  York  system,  or 
the  lower  division  of  the  Silurian  system  of  Mr.  Murchison." 
(Agriculture  of  New  York:,  pat^j  55.) 

§  91.  In  this  last  quoted  volume,  giving  the  results  of  his 
more  extended  • +udies,  it  is  said  that  "  the  Taeonic  slate,  with 
its  subordinate  beds,  occupies  almost  the  whole  of  Columbia, 
Rensselaer  and  Washington  counties  in  New  York,"  and  ex- 
tends eastward  to  the  base  of  the  Taeonic  hills,  on  the  frontier 
of  New  England.  Crossing  the  Hudson  from  Dutchess  county, 
it  was  subsequently  traced  through  Orange  county,  and  across 
northern  New  J'^rsey  into  J'ennsylvania,  and  thence,  along  the 
western  base  of  the  Blue  Kidge,  into  Virginia.  (Emmons, 
American  Geology,  page  117.) 

§  92.  The  meeting  of  the  Taeonic  slates  and  the  Hudson 
Kiver  (Loraine)  slates  was  said  to  be  visible  at  various  localities 
in  the  valley  of  the  Hudson,  along  the  western  side  of  which 
the  Loraine  slates  are  found  overlying  unconformably  the  Ta- 
eonic slates,  which  finally  pass  below  the  Loraine  in  the  valley 
of  the  Mohawk.  Other  meml>ers  of  the  Champhiin  division 
were  also  declared  to  rest  unconformably  u{)on  tlie  Taeonic  slates, 
to  the  east  of  the  Hudson.  In  his  volume  of  lS4(i,  Emmons  de- 
scribes a  section  from  Greenbush,  on  the  Hudson,  eastward  to 


46  E. 


SPECIAL   REPORT.      T.  STERRY    HUNT,  1875. 


Chatham  Four-Corners,  the  rooks,  a  scries  ol"  eastward-dipping 
shitea,  limestones  and  quartzites,  being  represented  throughout 
as  laconic,  witii  the  exception  of  small  outliers  of  Loraine 
shales  and  Calciferous  sandrock,  near  the  Hudson.  In  another 
section  across  the  Hudson,  at  I'ouglikeepsie,  the  strata  on  both 
sides  are  called  Taconic,  and  are  rejjresented  as  succeeded,  one 
mile  west  of  the  Hudson,  by  Hudson  River  (Loraine)  shales, 
(loc.  cit.,  plate  XVIII.)  The  continuation  of  this  section  east- 
ward from  Foughkeepsie  is  also  designated  by  hini  as  Tacouic. 
By  com[)aring  these  data  with  the  geological  map  of  New 
York,  and  with  the  statements  of  Mather,  given  above,  it  is 
clear  that  the  Taconic  slate  formation  in  eastern  New  York 
was  co-extensive  with  the  disturbed,  altered  and  anomalous 
Hudson  River  group  of  Mather,  and  that  the  included  and  un- 
derlying limestones  of  the  legion  were,  in  like  manner,  the  lime- 
stones of  the  Taconic  system  of  Emmons. 

§  93.  We  have  next  to  consider  those  overlying  rocks  which 
Mather,  in  this  region,  referred  to  the  Oneida  and  Medina  for- 
mations of  the  Ontario  division.  In  1842,  Emmons  placed  at 
the  summit  of  the  Loraine  what  he  called  the  Gray  band, 
which  he  considered  as  the  equivalent  of  the  Oneida,  and  in- 
cluded this,  with  the  Medina,  in  the  Champlain  division;  but 
in  184(j  he  transfer''ed  the  Medina  to  the  Ontario,  making  the 
Champlain  division  to  terminate  with  the  Gray  band  or  Oneida. 
Thus,  when  Mather  speaks  of  the  rocks  in  ijuestion  as  belong- 
ing to  the  lowei  part  of  the  Ontario  division,  and  Emmons  as- 
signs them  to  the  upper  part  of  the  Champlain,  it  will  be  un- 
derstood that  both  refer  them  to  the  same  horizon  ;  the  latter 
geologist  including  in  the  Oneida  certain  red  shales  regarded 
by  Mather  as  pertaining  to  the  Medina  formation, 

§  94.  Mather,  as  we  have  seen,  traced  these  overlying  rocks, 
with  the  help  of  Rogers  and  Horton,  from  New  Jersey,  through 
Orange  county.  New  York,  to  the  west  bank  of  the  Hudson 
river,  and  thence,  crossing  into  Dutchess  county,  along  the  east- 
ern side  of  the  Hudson,  through  Columbia,  Rensselaer  and 
Washington  counties,  to  West  Poultney  in  Rutland  county, 
Vermont,  near  the  head  ot  a-.,!.e  Champlain.  Emmons,  in  1842, 
referred  to  the  Oneida  the  sandstones  occurring  farther  north, 
along  the  east  side  of  this  lake,  in  the  towns  of  Addison,  Char- 


1 
( 
a 
I 
b 
t( 
ni 


EMMONS   ON    THE   TACONIC    SYSTEM 


E.  47 


lotto,  Burlington  and  Colcliester ;  while  the  liniestoiies  of  St. 
Albans,  Swanton  and  llighgate  were  suppotJed  by  him  to  be- 
long to  the  summit  of  the  Loraine.  lie  further  pointed  out 
that  these  rocks,  (regarded  collectively  as  belonging  to  the 
summit  of  the  Champlain  division),  extended  southward  from 
Vermont,  through  the  eastern  counties  of  New  York  already 
named,  where  they  had  been  studied  and  described  by  Mather, 
and  northeastward  through  Canada,  as  lar  as  (Quebec. 

§  95.  Between  1S42  and  1840  the  views  of  Enunons  vvith  re- 
gard to  these  rocks  had  undergone  a  complete  change,  and  he 
now  transferred  them  to  the  lower  part  of  the  Champlain  di- 
vision, and  regarded  them  as  a  modified  form  of  the  ('alcifer- 
ous  sand-rock  of  the  Mohawk  valley,  which,  to  the  eastward, 
he  declared  to  include  various  forms  of  rock,  and  to  be  "pro- 
tean" in  its  characters.  To  one  of  these  varieties  he  referred 
the  red  sandstones  of  Addison,  Charlotte  and  Burlington,  with 
their  interstratitied  red  and  chocolate-colored  slates,  and  de- 
clared that  these  sandstones,  through  an  admixture  of  carbon- 
ate of  lime,  pass  into  a  gray  calcareous  sandstone,  forming 
the  upper  part  of  the  series ;  while  beneath  the  red  sandstones 
were  beds  of  a  blue  compact  limestone,  sometimes  fossiliferous. 
This  limestone,  he  declared  to  be  the  lowest  member  of  the  se- 
ries, and  to  rest  directly  upon  the  Taconic  i)lack  slate. 

§  90.  This  whole  formation  was  supi)Osed  by  PJmmons  to  oc- 
cupy the  position  of  the  so-called  Calciferous  sandrock  of 
northern  New  York,  which  is  beneath  the  Chazy  limestone  and 
above  the  Potsdam  sandstone.  This  latter  formation,  accord- 
ing to  him,  was  wanting  in  eastern  \''ermont  and  eastern  Xew 
York,  as  well  as  in  the  valley  of  the  Mohawk,  where  the  Cal- 
ciferous rests  directly  on  the  Brimary.  An  irregular  belt  of 
this  motlitied  and  protean  Calciferous  sand-rock,  acci  rding  to 
Emmons,  is  traced  from  the  Canada  line,  through  eastern  Ver- 
mont, into  Xew  York.  "Ln  the  counties  of  Dutchess  and 
Orange  it  forms  an  imperfect  belt,  in  Columbia,  Rensselaer 
and  Washirigton  counties  its  continuity  is  still  more  broken. 
It  occupies  in  the  last  three  counties  the  knobs,  as  at  Green- 
bush,  Urcenwich  and  Whitehall.  These  knobs  lie  contiguous 
to  the  Hudson;  it  is,  however,  still  found  sparingly  twenty 
miles  east  of  the  Iluilson  river,  an  at  Iloosic,  and,  as  I  now  be- 


I 


48  E. 


SPECIAL  UEPORT.   T.  STERRY  HUNT,  1875. 


lieve,  near  Pownal,  Vermont.  *  *  *  Probably  this  broken 
ranL'"c  or  belt  runs  obliquely  across  Columbia  and  Dutchosg 
counties,  and  thence  onward  into  Orange,  crossiniii;  the  Hudson 
I'iver  a  few  miles  above  Newburg.  We  can  hardly  avoid  the 
inference  that  this  belt  was  once  continuous,  and  formed  an 
important  mass,  overlying  the  Taconic  slate."  *  *  *  In  the 
Jfudson  valley  insulated  patches  of  these  rocks,  sometime8 
limited  to  a  few  acres,  and  sometimes  miles  in  extent,  are  met 
with,  often  forming  tlie  highest  points  in  the  region.  In  favor- 
able localities  they  occupy  a  jiosition  not  to  be  mistaken,  and  rest 
upon  the  slates  of  the  Taconic  system.  The  liniestone,  which 
appears  at  the  base  of  this  series,  reposes  upon  the  upturned 
edges  of  the  Taconic  slates,  as  is  seen  in  many  quarries.  As 
the  result  of  the  great  fractures  and  disturbances  in  this  re- 
gion, the  rocks  of  the  ('alciferous  series  are  also  sometimes 
found  "in  the  valleys,  outcrop})ing  from  beneath  the  Hudson 
Uivcr  (Ijoraine)  slates  which  have  been  preserved  from  de- 
nudation."    (Agriculture  of  Xew  York,  pages  118-122.) 

§  97.  With  regard  to  the  overlying  rocks,  which  form  the  up- 
per members  of  the  Champlain  division,  the  Utiea  slate  has, 
according  to  him,  "but  a  slight  claim  to  the  distinction  of  an 
independent"  formation,  constituting,  as  it  does,  the  transition 
from  the  Trenton  limestone  to  the  Loraine  shales ;  and  in  or- 
ganic remains,  and  in  other  characters,  partaking  more  of  the 
characters  of  tjie  latter.  In  Jefferson  and  Lewis  counties  he 
remarks  that  there  is  an  alternation  of  strata  having  the  as- 
})ect  of  tlui  Utica,  with  the  Loraine  shales,  which  latter,  in  their 
upper  part,  alternate  with  the  thick-bedded  sandstones  of  the 
(ilray  band,  already  mentioned,  so  that  it  is  not  easy  to  define 
the  liniits  of  the  two.  These  heavy  beds  of  the  Loraine  are 
seen  in  the  valley  of  the  Rondout  in  many  places  east  of  the 
High  Falls,  on  the  Hudson  and  Delaware  canal, and  to  great  ad- 
vantage at  their  northern  outcropping  along  the  termination 
of  the  Helderberg  range,  v, ;  ere  appear  alternating  beds  of 
sandstone  and  black  slate,  the  latter  from  twelve  to  eighteen 
inches  in  thickness.  About  700  feet  of  these  strata  are  there 
exposed,  with  a  slight  dip  to  the  south-west.  "It  is  here  al- 
most destitute  of  fossils,  and  in  thisresjiect  resendjles  the  beds 
which  occur  in  patches  upon  the  east  side  of  the  Hudson,  along 


ROCKS   OF    THE    CHAMPLAIX    DIVISION. 


E.  49 


the  Western  (Boston  and  Albany)  niiUvay.  These  latter  beds 
may  be  clearly  di-itinguifihed  from  the  slates  and  shales  of  the 
Taconie  system  ;  they  neither  conform  with  them  in  dip  nor  in 
strike,  and,  except  in  the  immediate  vicinity  of  the  great  north- 
ern fracture  of  tlie  Hudson  valley,  their  di[)  and  disturbance  are 
not  excessive."  These  rocks  are  said  to  forma  small  range  be- 
tween  Chatham  Centre  and  Chatham  Four-Corners,  where  they 
lie  in  deep  troughs,  and  are  exposed  in  the  railway  cuttings." 
(Agriculture  of  Xew  York,  pages  128-125,  128.) 

§  98.  According  to  these  statements  of  Emmons,  we  have 
then  in  the  region  of  sedimentary  rocks,  along  the  valley  of 
the  Hudson,  three  distinct  series  of  strata:  I.  the  slates  and 
limestones  of  the  Taconie  series  ;  II.  The  sandstones,  slates  and 
limestones  belonging  to  the  Calciferous  sand-rock  of  the  Cham- 
plain  division,  resting,  in  ajijiarent  unconformity,  ujion  the  for- 
mer, and  partially  removed  by  erosion  before  the  deposition  ot 
III,  a  series  of  shales  and  sandstones  belonging  to  the  sni)erior 
portions  of  the  Champlain  division,  which  have,  in  their  turn, 
been  to  a  great  extent  eroded,  but  are  found  in  patclies  over- 
lying, unconformably,  alike  the  strata  of  I  and  of  II. 

§  99.  This  condition  of  things  im})lie8  that  there  occurred  a 
change  of  level  immediately  preceding  the  time  of  the  Utica 
and  Loraine  formations,  (IIF,)  which  allowed  these  to  be  depos- 
ited not  only  on  the  Trenton  limestone,  but  also  on  the  older  se- 
ries, (T  and  II.)  That  such  was  really  the  case  is  evident  from 
other  facts.  The  Laurentian  region  of  the  Adirondacks  and 
Laurentides  was  not,  at  this  time,  as  has  been  so  often  said,  the 
nucleus  of  a  growing  continent,  but  one  of  the  higher  parts  of 
a  subsiding  one,  and  the  deposition  of  the  rocks  of  the  Cham- 
plain  division  was  marked  by  more  than  one  period  of  disturb 
ance.  Upon  its  ancient  gneiss  we  find  reposing  directly,  in 
in  different  localities,  the  Potsdam,  the  Calciferous,  the 
Trenton  and  the  Utica  formations.  The  deposition  of  the 
Trenton  marks  a  time  of  subsidence,  during  which,  along  the 
Laurentides,  the  deep  sea  extended  far  and  wide  to  the  north, 
and  the  marine  limestones  of  the  Trenton,  overlapping  the 
lower  members  of  the  Champlain  division,  were  deposited  over 
the  regions  to  the  north  of  Lake  Ontario  and  of  the  lower  St 
Lawrence,  (and  as  far  northeastward  as  the  basiu  of  Lake  St. 
4— E. 


If 

i 


50  E. 


SPECIAL   REPORT.       T,  STERRY    HUNT,  1876. 


I 


John, on  the  Sagueiuiy,)  directly  upon  the  submerged  Primary 
or  Euzoic  rocks. 

§  100.  After  this  period,  and  betore  the  succeeding  time  of 
the  deposition  of  mechanical  sediments,  extensive  movements 
took  place  in  the  regions  of  the  Ottawa  valley  and  Lake  Cham- 
plain,  which  allowed  tiieso  sediments  to  he  laid  down  alike  on 
the  I'rimary  rocks  and  on  the  older  members  of  the  Cluimplain 
division.  Evidence  of  this  can  be  seen  on  the  geological  map  of 
Canada,  where,  on  the  northern  border  of  the  Ottawa  basin,  and 
immediately  south  and  east  of  the  city  of  that  name,  is  shown, 
in  the  counties  ot  Carleton  and  iiussell,  an  isolated  patch  of 
Utica  slates,  overlaid  with  gray  calcareous  sandstones,  holding 
the  fossil  remains  of  the  Loraine  and  associated  with  red 
shales.  This  outlier,  which  has  its  greatest  length, about  twenty 
miles,  from  east  to  west,  reposes  trausgressively  alike  upon  the 
Calciferous,  Chazy  and  Trenton  formations,  all  three  of  which, 
with  a  slight  eastward  dip,  towards  the  centre  of  the  basin, 
ajipear  successively,  in  passing  from  west  to  east  along  the 
southern  border  of  this  unconformably  overlying  area  of  the 
newer  strata  of  the  Chamjdain  division,  which  are  here  let  down 
along  the  north  side  of  an  east  and  west  dislocation.  (Geology 
of  Canada,  pages  118,  127,  1(35,  219.) 

§  101.  Ennnons  has  described  an  analogous  occurrence  in  the 
valley  of  Lake  Cham])lain,  where,  in  Essex  county,  near  Split 
ivock,  on  the  south  side  of  Whallon's  bay,  the  Utica  slates 
overlap  the  older  members  of  tl»e  Champlain  scries,  and  "  rest 
visibly  upon  the  Primary"  or  ancient  crystalline  rocks  of  the 
region.  (Geology,  Second  district,  page  278,  and  plate  VIII, 
section  4.) 

§  102.  In  1855,  ajipeared  parts  I  and  II  of  the  "American  Ge- 
ology "  by  Prof.  Emmons.  The  second  of  these  is  devoted  to  an 
exposition  of  the  Taconic  system  and  of  the  Champlain  division 
of  the  New  York  series,  and  may  be  sup])Osed  to  contain  the 
author's  final  conclusions  with  regard  to  the  imi)ortant  ques- 
tions raised  in  his  publications  of  1842  and  1846.  In  1842 
he  included  in  the  Taconie  system  the  granular  limestones 
of  Stockbridge,  the  granular  quartz  rock,  the  so-called  mag- 
uesian  8lates,and  the  sparry  limerock,  besides  a  group  of  strata, 
not  very  clearly  defined,  designated  by  him  as  the  Taconic 


EMMONS  ON  THE  TACONIC  SYSTEM. 


E.  51 


slates  ;  the  order  of  succession  aniono;  all  these  beins:,  accord- 
ing  to  Emmons,  unsettled,  or  "at  least  not  clearly  establislied." 
The  line  of  deniarkation  between  the  Taconic  slates  (the  Tran- 
sition Argillite  formation  of  Eaton)  and  the  Xew  York  series 
was.  also  undetermined,  and  the  roofing-slates  of  Iloosic,  and 
some  other  localities  in  that  region,  were  then  referred  to  the 
latter,  in  deference  to  the  opinions  of  his  colleagues,  though, 
as  he  tells  us  in  1846,  contrary  to  his  own  judgment.  Certain 
organic  forms,  resembling  the  graptolites  of  the  Utica  forma- 
tion, found  in  these  slates,  were,  in  1842,  regarded  as  evidence 
that  they  belonged  to  the  New  York  series,  but  subsequently 
Emmons  came  to  regard  them  as  marine  plants,  of  wliich  he 
describes  some  with  narrow  and  others  with  "  wide  fronds.'' 
One  of  these  supposed  plants  from  Hoosic  was  figured  by  him  in 
1846,  under  the  luime  of  Fucoides  simplex.  (Agriculture,  New 
York,}»age  71, and  pi.  XVII,  tig.  1.)  This,  according  to  Hall,  had 
been  previously  named  by  ^•Aton,  Fucoides  secalinus,  and  wasl)y 
Hall,  in  1865,  called  Gr<iptolithn.<  {Diplograptus)  secalinus.,  and 
referred  by  him  to  the  so-called  Quebec  group.  It  is,  however, 
undescribed.  (James  Hall,  Geol.  Survey  of  Canada,  decade  II, 
pp.  57, 64.)  Ennuons  had  already,  in  1855,  recognized  the  grapto- 
litic  character  of  the  organic  remains  from  the  Iloosic  slate. 
(American  Geoh)gy,[I,  [»age  40.) 

§10o.  In  1846,  tlie  succession  of  the  Taconic  rocks  was  de- 
fined by  Emmons  as  follows,  in  ascending  order:  (1)  Qranuhir 
quartz  rock  ;  (2)  Maguesian  slate;  (3)  Stockbridge  limestone, 
which  was  declared  to  be  interstratified  with  the  Magnesiaii 
slate,  so  that  the  two  were  to  be  regarded  as  forming  but  one 
rock.  To  these  succeeded  (4)  the  Taconic  slate,  under  wliich 
head  was  included,  besides  a  soft  Maguesian  slate,  reseml)liug 
tluit  below  the  Stockl>ridge  limestone,  a  great  variety  of  other 
rocks.  Among  these  were  coai*se  greenish  chloritic  sandstones, 
gray  sandstones;  limestones,  gray  and  silicious,  blue  and  com- 
pact, and  sparry  and  brecciated ;  besides  coarse  and  fine  slates, 
green,  black,  red  and  chocolate-colored,  together  with  tine- 
grained  n)ofing-slates.  (Agriculture, New  York, page66.)  Above 
this  heterogeneous  group,  included  under  the  common  name  of 
Taconic  slates,  was  placed  a  black  slate,  sometimes  including  cal- 
careous beds,  which  was  regarded  as  the  summit  of  the  Taconic 


52  E. 


SPECIAL    REPORT.      T.  STEIIRY    HUNT,  1875. 


i 


system.  It  was  in  this  slate,  on  Bald  Mountain,  in  Washinoj- 
ton  county.  New  York,  that  were  found  the  trilobites  described 
by  Emmons  as  Atops  trilineaius  and  Elliptoccphala  asaphoides. 
(Ibid,  pa^e  64.)  lie  afterwards  supposed  that  tliere  are  in  the 
region  described,  on  the  frontiers  of  New  York  and  Massachu- 
setts, roofiiiir-slates  at  two  horizons  in  the  Taconic  system ;  tlie 
one,  a  tine  blue  slate,  occupying  a  position  lu'low  the  sparry 
limestone,  and  the  other  above  this  limestone,  including  the 
slates  of  Iloosic,  which  yield  the  graptolitic  forms  already 
noticed.     (Amer.  Geology,  II,pages  39-41.) 

§  104.  In  1855,  Emmons  proposed  to  divide  the  Taconic  sys- 
tem into  two  parts,  which  he  called  respectively  Lower  and 
Ui»per  Taconic,  and  between  which  "the  line  of  demarkation 
is  tolerably  well  defined."  The  Lower  Taconic  includes  the 
Granular  quartz  rock,  at  the  base,  the  Htockbridgc  limestone, 
with  its  associated  Magnesian  slates,  (to  which  the  name  of  tal- 
eose  slates  was  then  given,)  ajid  terminates  with  the  similar  slate 
overlying  the  limestone.  (Ibid,  TI,  i)age  12.)  Further  (m,  he 
describes  with  some  detail,  the  Lower  Taconic  series  as  seen 
in  Williamstown  and  Adams,  in  Berkshire  county,  Massachu- 
chusetts.  The  lowest  division  of  this  series  has,  at  its  base,  a 
conglomerate  of  rounded  and  angular  pebbles  of  quartz  in  a 
talcose  paste.  This,  in  some  points,  rests  upon  a  granitic  rock, 
of  which  it  then  includes  the  fragments.  Succeeding  this 
there  are  several  repetitions  of  quartzose  sandstones  and  con- 
glomerates, with  soft  talcose  slates,  iiaving  an  aggregate  thick- 
ness of  about  1,200  feet,  which  are  well  seen  in  Oak  Hill,  de- 
scribed as  a  synclinal  mountain  rising  1,700  feet  above  the  val- 
ley of  the  Iloosic.  Above  this  comes  the  Stockbridge  lime- 
stone, 500  feet  in  thickness,  and  more  or  less  interlaminated 
with  the  talcose  slates.  2,000  feet  of  similar  slates,  overlie  the 
limestone,  and  are  seen  in  Saddle  and  (iraylock  Mountains; 
thus  making  the  entire  thickness  of  the  Lower  Taconic  series 
in  this  region  about  3,700  feet.     (Ibid,  II,  pages  15-18.) 

§  105.  The  same  succession  and  similar  characters  are  b^-  Em- 
mons ascribed  to  the  Lower  Taconic  rocks  in  their  southward 
extension  through  Pennsylvania,  Virginia,  North  Carolina 
Tennessee  and  Georgia.  He  has  given  the  details  of  a  section 
which  is  well  displayed  at  the  Warm  Springs,  in  Buncombe 


LOWKR  AND  UPPER  TACONIC  SERIES. 


E.  63 


county,  North  Carolina,  on  the  Frcncli  Broad  river.  The 
Lower  Taconic  strata  rest  unconforniably  upon  tlie  ancient 
gneisses,  (which  here  dip  to  the  south-east,)  and  are  inclined  to 
the  west,  the  measured  thickness  being  about  3,C00  feet. 
(Amer.  Geoloijy,  II,  page  24.) 

§  106.  In  his  "Manual  of  Geology,"  published  in  1860, 
the  Lower  Taconic  is  described,  in  general  terms,  as  cou- 
pisting  of  a  conglomerate  at  the  base,  succeeded  by  three 
masses  of  quartzite  or  sandstone,  separated  by  talcose  slates; 
tbe  upper  quartzite  being  often  vitreous,  while  the  lower  is  a 
sandstone.  To  this  succeed,  as  before,  the  granular  limestones, 
with  their  associated  and  overlying  slates,  (including some  roof- 
ing-slates,) the  total  thickness  being  about  5,000  feet. 

§  107.  The  Upper  Taconic  series  is  very  distinct  in  its  charac- 
ters from  the  Lower  Taconic,  and  comprises  the  various  rocks 
which  have  been  described  as  l)elongiug  to  the  Taconic  slates. 
It  has,  at  its  base,  coarse  slates  and  eandstones,  which  aregreeii- 
ioh  in  color,  the  masses  often  resembling  a  greenstone,  and  lieing 
"  rather  chloritic  than  talcose."  Chlorite,  and  "  perhaps  tbe  de- 
bris of  hornblende"  are  said  to  be  present  in  these  rocks,  and  a 
chloritic  matter  is  described  as  forming  in  many  cases  the  paste 
of  the  sandstones  and  conglomerates,  which  belong  to  the  base 
of  this  series  and  often  rest  upon  the  crystalline  rocks.  The 
higher  part  of  the  Upper  Taconic  is  said  to  be  very  variable  or 
"  protean"  in  character;  including  brown- weathering  calcareous 
sandstones  and  olive-colored  sandstones,  beds  of  quartzite,  with 
green,  purple  and  red-roofing  slates,  blue  limestones  and  spariy 
limestones;  while  towards  the  summit  are  conglomerates  with 
black  shaly  limestones,  the  series  terminating  with  a  fine  black 
slate.  This  description  niaj'  be  compared  with  that  previously 
given  of  the  Taconic  slate  grouj).  (§  103.)  The  upper  part  of 
this  Upper  Taconic  series  is  tbssiliferous,  containing  remains  uf 
graptolites,  fucoids  and  crustaceans.  (American  Geology,  II, 
pages,  12, 13,  50.) 

§  108.  The  Upper  Taconic  series  is  displayed  in  a  section  from 
near  Comstock's  Litndinsi;,  in  Wash iny; ton  county,  New  York, 
eastward  for  ten  miles  to  Middle  Granville.  The  series,  (hav- 
ing an  average  dip  of  40^  to  the  eastward,)  begins,  to  the  west- 
ward, with  thin  black  shttes,  and  ends,  to  the  eastward,  with 


54   E.  SPECIAL   BEPORT.       T.  STERRY    HUNT,  187o. 


ii 


thick-bedded  greenish  chloritic  8andstone8  and  conglomerate!". 
Tliere  is  in  this  series  no  representative  of  the  granuhir  (piartz 
ites,  the  limestones,  or  the  talcose  slates  of  tlie  Lower  Taofwiic, 
and  "  the  roofing-slates  of  Columbia  and  Rensselaer  counties 
are  absent."  To  the  westward  of  this  section,  at  Comstock's 
Landing,  the  Potsdam  sandstone  is  seen  to  rest  upon  the  gneiss, 
iind  jiasses  eastward  below  the  overlying  Calcil'erous  saiidrock 
and  Chazy  limestone.  Further  eastward,  the  Calcilerous,  with  its 
i-liaracteristic  tbssils,  is  seen  to  rest  unconformably  upon  the  beds 
of  the  Taconic  slate.  The  Upper  Taconic  series,  it  will  be  un- 
derstood, here  makes  its  apjiearance  from  beneath  the  lower 
members  of  the  New  York  series,  by  which  the  contact  of  the 
Primary  gneiss  with  the  Upper  Taconic  rocks  is  concealed. 
(American  Geology,  II,  page  52.) 

§  lUO.  The  Upper  Taconic  rocks  in  this  section  dip  to  the  east- 
ward at  an  angle  of  about  40°,  so  that  the  black  slates,  at  its 
western  end,  seem  to  pass  beneath  all  the  other  members,  and 
the  green  sandstones,  at  the  eastern  end  of  the  section,  appear 
to  overlie  all  the  others.  This  is  directly  contrary  to  the  suc- 
cession alroady  given,  where  the  green  sandstones  are  declared 
to  be  at  the  base,  and  the  black  fossiliferous  slates  at  the  sum- 
mit of  the  series.  This  apparent  inversion  is,  as  we  liave  al- 
roady seen,  the  general  condition  of  the  stratif '^d  rocks  ak)ng 
tiie  eastern  base  of  the  Athintic  belt  farthei  southward,  in 
New  York  and  along  the  Blue  Ridge,  as  described  by  Rogers 
;ind  by  Mather.  The  latter,  as  shown  in  §  72,  declares  that  along 
the  eastern  border  of  New  York,  in  the  Southern  district,  the 
newer  strata  of  the  Hudson  River  slates  dip  eastward  at  high 
angles,  apparently  passing  beneath  the  older  ones,  which  in  their 
turn  seem  to  plunge  beneath  the  ancient  gneisses. 

§  110.  This  condition  of  things,  (which  applies  alike  to  the 
Lower  and  the  Upjter  Taconic  rocks,)  was  described  by  Emmons 
in  1841,  when  he  declared  that  "their  present  position  is  an 
inverted  one ;"  the  newer  rocks,  or  those  to  the  west,  diji  east- 
wardly  beneath  the  older,  or  might  evi'U  })ass  beneath  them, 
provid(!d  they  were  prolonged  in  that  direction."  He  sup{iosed 
tiiat  the  newer  portions  of  the  series  might  have  been  origin- 
ally contined  to  the  western  parts  of  the  area,  and  never  have 
extended  so  far  east  as  to  cover  the  basal  beds  near  the  I'rimary 


THE    Ul'I'KK   TACONIC    ROCKS. 


E.  55 


gneias.  lie  fivrthermorc  supposed  the  movement,  which  had 
given  to  the  whole  succession  an  eastward  dijt,  had  heen  accom- 
panied by  a  series  of  dislocations,  with  uplifts  on  the  eastern 
side  of  the  faults.  He  remarks,  in  this  connection,  that  "the 
force  which  breaks  the  continuity  of  the  strata  exerts  its  maxi- 
mum power  nearest  the  mountain-chain,''  and  notes  that  in  the 
Williamstown  section  (§  104)  not  loss  than  tive  distinct  disloca- 
tions of  this  kind  may  be  observed  in  a  breadth  of  a  few  miles. 
(Agriculture,  New  Yotk,  [i.  (51,  and  Amer.  Qeol.  II,  i'i».  48-4t).) 
Such  a  condition  of  things  is  completely  analogous  to  the  great 
parallel  faults,  with  upthrows  on  the  south-east  side,  described 
by  AV.  B.  Rogers,  and  by  Lesley,  in  south-western  Virginia,  by 
which  the  carboniferous  rocks  are  made  to  dip  to  the  south-east, 
apjiarontly  beneath  nmch  older  strata. 

§  111,  The  Granville  section  of  the  Upper  Taconic  rociks,  al- 
ready noticed,  is  supposed  by  p^mmons  to  havea  total  thickness 
of  not  less  than  25,000  feet,  but  it  is  evident  that  dislocations 
like  those  just  described,  which  may  give  rise  to  repetitions, 
must  add  greatly  to  the  difficulty  of  measuring  such  a  iieries 
of  strata. 

Those  Upper  Taconic  rocks  are  traced  b}'' Emmons  southward 
through  Washington,  Rensselaer  and  Dutchess  counties,  and  are 
said  It}^  him  to  cross  the  Hudson  below  Poughkeefisie,  passing 
through  Orange  county,  into  New  Jersey,  and  thence  to  Pennsyl- 
vatiia  and  Virginia.  In  tlie  latter  state  a  section  of  these  rocks 
is  described  near  Wytheville,  and  another  from  Abingdon,  on 
the  road  leading  to  Taylorsville,  Tennessee,  in  each  of  which 
both  the  Ujtper  and  Lower  Taconic  rocks  are  declared  to  be  well 
disy»layed.     (Amer.  Geology,  II,  pages  (>1-61.) 

§  112.  The  reader  will  note  that  in  the  account  of  tlie  Taconic 
system  by  Emmons  in  1842,  tiiere  is  no  description  given 
of  the  gr3at  mass  of  strata  which  make  the  Upper  Taconic,  as 
defined  by  him  in  1855.  There  evidently  existed  in  his  mind 
at  this  earlier  date  much  uncertainty,  which  is  reflected  in  his 
writings.  Thus,  in  his  report  of  1842,  the  rocks  of  the  Taconic 
system  were  declared  to  extend  through  the  eastern  counties 
of  New  York,  from  the  Highlands,  beyond  whicli  "they  are  found 
stretching  through  whole    length  of  Vermont,  and  into 

Canada,  as  far  as  Quebec."     (loc.  cit.  page  130.)     In  a  previ- 


66  E. 


SPECIAL    KEI'OHT.       T.  STEUUY    HUNT,   \Hl'). 


ous  chapter,  in  the  same  volume,  we  are  told,  (page  121)  under 
the  head  of  the  New  York  system,  that  a  belt  of  deep  red  and 
purple  shales,  i)as8ing  into  a  fine-graMied  gritty  sandstone,  ex- 
tends throuy-liout  these  same  counties  in  New  York  ''and  onward 
through  Vermont  into  Camida.''  No  locality  in  Canada  Wiis 
indicated,  hut  these  slates  and  sandstones  were  relcM-red  to  the 
Loraine  shales,  of  which  they  were  considered  a  local  variation, 
unknown  in  the  valley  of  the  Mohawk;  while  a  greenish  chlo- 
ritic  sandstone  or  breccia,  described  as  a  tyj»ical  Graywacke, 
(which  is  placed  at  the  summit  of  the  Loraine,)  is  said  to  be  the 
material  used  at  Quebec  for  the  construction  of  the  I'ortitioa- 
tions  of  the  city  (page  12').)  Farther  on  in  the  same  volume, 
tiie  sandstones  (Graywacke)  of  Addison,  Vermont,  as  seen  in 
Snake  Mountain,  and  those  of  Charlotte  in  the  same  state,  are 
described  as  gray,  or  reddish-brown,  and  sometimes,  like  their  as- 
sociated slates,  as  having  a  greenish  chloritic  coloring.  These 
sandstones  anrl  slates  of  Charlotte  are  spoken  of  as  belonging 
to  a  range  extending  from  Columbia  county.  New  York,  to  the 
Canada  line,  and  as  occupying  a  position  immediately  below 
the  Medina  sandstone,  or  at  the  summit  of  the  Loraine  shales; 
the  limestones  of  the  Chazy  and  Trenton  apjioaring  to  dip  be- 
neath the  Graywacke  series.     (Pages  280-282.) 

§  113.  Near  the  city  of  Quebec,  with  the  geology  of  which 
Emmons  was  familiar,  there  are,  besides  the  ancient  gneisses, 
two  series  of  rocks  ;  one  the  nearly  horizontal  strata  of  the 
New  York  series,  including  the  Trenton,  Utica  and  the  overly- 
ing typical  Loraine  shales,  (all  of  which  were  there  recognized 
by  Emmons);  and  the  other,  the  highly  inclined  group  of  strata 
which  consist  in  their  upjier  part  of  red  and  purple  shales,  and 
are  terminated  by  the  greenish  chloritic  sandstones  of  Sillery, 
which  are  those  used  in  the  construction  of  t)ie  fortifications  of 
(Quebec.  These  rocks  are  tracsed  from  this  locality  south-east- 
ward, to  the  frontier  of  Vermont,  along  the  western  base  of  the 
hills  of  crystalline  rock,  and  there  is  nothing  throughout  the 
whole  extension  which  resembles  the  cpiartz-rock  or  the  lime- 
stones of  the  Lower  Taconic  series.  It  seems,  therefore,  im- 
possible to  come  to  any  other  conclusion  than  this, — that  the 
Taconic  rocks,  which  were  by  Emmons,  in  1842,  declared  to  ex- 
tend from  Vermont  to  Quebec,  are  the  same  with  those  which 


THE   UPPEK   TACUNIC    R0CK6. 


K  57 


lie  t'lsewlicre,  in  the  same  volume,  de^*cril)es  as  rocks  belonging 
to  the  summit  of  the  Ch;implaiii  division,  uinl  having  the  same 
distribution.  This  conclusion  is  further  strengthened  by  the 
fact  that  what  he  described  in  1855  as  the  Upiier  Taconic  se- 
ries has  actually  been  traced  from  Vermont,  along  the  line  just 
indicated,  to  the  city  of  (Quebec,  the  vicinity  of  which  affords 
a  characteristic  section  of  much  oi  the  series.  The  student  of 
the  works  of  Emmons  will  iind  in  them  other  examjilus  of 
apparent  discrepancies  and  contradictions,  which  arc,  however, 
easily  explained  by  the  disjointed  and  fragmentary  torm  of 
his  writings  ;  in  which  unity,  method  and  literary  skill  are,  un- 
fortumitely,  wanting.  These  defects  have  contributed  not  a 
little  to  the  undeserved  neglect  with  which  his  very  valuable 
contributions  to  American  geology  have  hitherto  been  uenerally 
treated. 

§  114.  In  1846,  as  we  have  already  noticed,  the  grny,  reddish- 
brown  and  greenish  sandstones  and  slates  of  Addison,  Char- 
lotte, Burlington  and  St.  Albans,  (which,  like  the  similar  ones 
of  Quebec,  were,  in  1842,  referred  in  one  chapter  to  the  summit 
of  the  Loraine  shales,  and  in  another  chapter  apparently  con- 
founded with  the  Taconic,)  were  regarded  as  pertaining  to  the 
Calciferous  sandstone.  This  was  described  as  a  formation 
protean  in  its  aspects  in  this  eastern  region,  and  was  traced,  as 
we  are  told,  throughout  the  state  of  V  ermont  and  the  eastern 
counties  of  New  York,  till  it  crosses  the  Hudson  river  a  few 
miles  above  Newburg  and  passes,  as  an  interrupted  belt, 
through  Orange  county.  (Agriculture,  New  York,  pages  120- 
121.)  It  was  not  at  this  time  clearly  distinguished  from  the 
Taconic  slates,  upon  which  it  was  said  to  rest,  and  when  later 
(in  1855)  the  chief  })art  of  these  slates  was  raised  to  the  rank 
of  a  distinct  series,  under  the  name  of  Upper  Taconic,  flie 
greenish  chloritic  sandstones  of  tiiis  region  were  included 
therein.  The  red  sandstone  of  Burlington  was  now  declared 
to  be  Potsdam,  though  some  of  the  beds  associated  witli  it 
were  still  included  in  the  Calciferous.  ( Amer.  Geol.,  II,  pp.  88, 
128.)  Subsequent  studies  in  this  region  help  to  explain  this 
confusion,  by  showing  that  these  rocks,  whether  called  Loraine 
and  Oneida,  or  Calciferous  and  Potsdam,  are  but  parts  of  the 
Upper   Taconic   series,  and   are  the   same   with  those   which 


58  E. 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


I 


Matlier,  in  the  southern  part  of  their  extension,  referred,  in 
1843,  to  u  horizon  nearly  coinciding  with  the  highest  of  those 
just  named  ,  namely,  the  base  of  the  Ontario  division,  includ- 
ing the  Oneida  and  Medina  formations — the  red  slates  being,  ac- 
oniing  to  him,  above  and  not  below  the  sandstones. 

§  115.  Emmonts,  in  liis  successive  works,  makes  no  allusion  to 
his  repeated  clianges  of  opinion  with  regard  to  these  rocks,  so 
that  the  student  who  has  not,  with  critical  care,  followed  their 
history  in  his  i)ages,  fails  to  find  the  Key  to  the  contradictions, 
both  real  and  ap[iarent,  which  they  contain.  In  his  "American 
Geology,"  (li,  page  88,)  in  treating  of  the  red  sandstone  of  east- 
ern Vermont,  which  is  there  siioken  of  as  Pott  dam,  reference 
is  made  to  "the  error  which  has  been  committed"  in  regarding 
this  rock  as  the  Medina  sandstone;  leaving  the  reader  to  infer 
that  the  error  was  committed  by  some  geologist  other  than  the 
writer,  ^o  further  reference  is  there  made  by  Emmons  to  his 
earlier  views,  and  his  fubserpient  publications  throw  but 
little  additional  light  on  the  Taconic  system.  In  his  report 
on  the  "  Geology  of  the  Midland  Counties  of  North  Carolina," 
(lSo(),)  i)ages  43-72,  will,  however,  be  found  some  few  details  on 
tlic  Taconic  rocks  in  that  region  ;  and  his  "  Manual  of  Geology" 
(1860)  may  be  read  with  advantage  in  this  connection. 

£  116.  It  is  proper,  in  this  place,  to  notice  the  views  and  the 
observations  of  the  late  Prof  C.  B.  Adams,  who,  in  a  communica- 
tion to  <iie  American  Association  of  Geologists  and  Xaturalists, 
in  1846,  after  Enmions  had  declared  the  red  sandstone  of  Ver- 
mont to  belo!ig  to  the  base  of  the  Cluunplain  division,  and  to 
rest  upon  the  Taconic  slates,  still  held  to  the  view  that  both  of 
these  rocks  are  included  in  the  up[ier  [»ortions  of  the  same 
Chamjilain  division.  01'  the  nortli  part  of  Addison  county, 
Vermont,  iu'  said:  "One  Oi  the  most  conspicuous  rockti  of  this 
region  is  a  Red  sand-rock,  whicli  Dr.  Ennnons  regards  as  at  or 
near  the  base  of  the  New  York  series,  but  whicli  overlies  the 
Chamjilain  division  in  the  (descending)  order  ot  K«h1  sand- 
rock,  Hudson  River  (Loraine)  shales,  Utica  slates,  Tren- 
ton limestone,  and  La  Morte  limesto.ie.  A  section  was 
exhibited  of  Snake  Mountain,  in  whicli  these  rocks  appear, 
by  an  iplift,  with  their  relative  positions  unaltered.  The  two 
lower  formatioi  -  are  identified  hy  their  appropriate  fossils. 


ADAMS    AND    ROGERS   ON   TACONIC    ROCKS. 


E.  59 


wliieh  occur  abundantly ;  the  Utica  slate  by  its  position  and 
lithologieal  characters;  the  Hudson  River  shales  ])y  the  same 
characters,  and  by  tlieir  upper  member,  which  is  an  arijiilaceous 
limestone,  containing  the  stinted  forms  of  Chcetetes  lyopcrdoUy 
which  are  usual  in  this,  tiie  last  period  of  the  existence  of  the 
species.  The  Red  sand-rock  lies  upon  the  last  named  rock,  in 
actual  contact,  with  a  moderate  easterly  dip.  The  upper  ]iart. 
of  the  Mectioji  is  re{»eated,  in  the  line  of  strike,  in  several  othei 
localities,  but  one  only,  Buck  Mountain,  three  miles  north,  has 
sullicient  elevation  and  stee}tness  lO  exhibit  the  lower  part  of 
the  series." 

§  117.  "The  assertion  which  had  been  made  (by  Ennnons)  that 
there  is  a  line  of  fracture  high  up  the  side  of  Snake  mountain, 
above  the'f'renton  limestone,  was  shown  to  be  entirely  unsuppor- 
ted by  facts.  Not  only  is  there  no  evidence  that  such  a  line  ot 
fracture  has  brought  up  the  shales  from  beneath  the  Trentuu 
limestone,  but  the  fossils  in  the  ujipcr  member  of  the  shidcs 
[trove  that  the  present  is  tlieir  original  relative  })Osition.  Uiit 
these  are  the  Taconic  slates  of  the  Taconic  system.  From  its 
position  it  may  therefore  be  inferred  that  the  Red  saudrock  is 
more  recent  thiin  any  of  the  Champlain  division.  Its  fossils 
afford  less  demonstrative  evidence."  Adams  found  a  trilo])ite 
which  he  reg;a'ded  as  resembling  Conoeep/icUus,  together  with 
an  Atrypit„  and,  the  hori^ion  of  the  crustacean  not  being  tlicn 
well  known,  referred  the  Red  saudrock  to  "  the  ]>eriod  of  the 
Medina  sandstone  and  the  Clinton  group."  (Proc.  Anier.  As- 
Bociation  of  Geologists,  Boston,  1840  ;  iti  Amer.  Jouriial  of  Sci- 
ence, [-2]  V.  108.) 

§  118.  The  Red  sand-rock  of  this  region  is,  in  its  turn,  over- 
laid by  a  scries  of  limestones,  which  were  noticed  bv  Adams, 
and  subseqently  described  more  particularly  by  Prof.  W.  B. 
Rogers.  In  following  the  sections  from  the  western  base  of 
Snake  or  of  Buck  Mountain,  he  declan's  that  "we  ascend  through 
the  varicHis  divisions  of  the  Matimil  series,  from  the  Trenton 
to  the  top  of  the  Hudson  River  group,  *  *  *  eueh  marked 
by  cliaracteristic  fossils,  and  all   maintaining  a  nearly  uniform 

the  latter,  we  find  a  scries  of  red  iind 
idstones  and  shales,  of  ij-reat  tl 


<iii). 


gi 


gray 


:nes3. 


succeeded,  wheiH'  tlie   exposures  are   unbroken,  by   arenaceous 


60  E. 


SPECIAL    REl'ORT.      T.  STKRKY    HUNT,  1875. 


and  iirgillaceous  re'lilLsh  and  gray  limestones,  alternating  with 
beds  (if  sandstone  similar  to  that  beneath.  Stratigruiihically 
considered,  this  series  of  beds  occupies  the  position  of  the  Me- 
dina group  of  2^'evv  York,  or  its  equivalent,  the  Levant  se- 
ries of  Pennsylvania  and  Virginia.  *  *  *  In  the  prolonga- 
tion of  this  belt  of  sandstones  and  limestones  towards  the  nortli, 
as  at  W'inooski  Falls,  near  Burlington,  tlie  latter  mass  is  seen 
to  consist,  in  great  part,  of  a  purplish-white,  Une-grained  lime- 
stone, "which,  towards  the  base,  contains  layers  of  reddish 
limestone,  interstratilied  with  red  sandstone."  No  fossil  re- 
mains were,  by  him,  found  in  this  limestone,  which  he  regarded 
as  probably  "a  peculiar  development  of  the  u[t[)er  portion  of 
the  Medina  group." 

§  119.  The  above  extracts  from  a  [taper  written  by  Kogers, 
and  presented  to  the  American  Association  for  the  Advance- 
ment of  kScience,  in  1851,  were  again  read  by  him  before  the 
Boston  Society  of  Natural  History,  in  18G0,  on  the  occasion  of 
the  presentation  of  a  paper  by  I'rot.  C.  11.  Hitchcock,  which 
is  thus  resumed.  "The  two  most  interesting  points  in  this 
connection  were,  that  there  is  no  foundation  for  what  Mr.  Em- 
mons called  his  Taconic  system  (a  mixture  of  the  Silurian  and 
Devonian) ;  and  tlmt  the  Dorset  limestone  (his  Stockbridge 
limestone)  is  newer  than  the  Lower  Silurian,  and  probably  U[)- 
per  Silurian  or  Devonian."  (Proc.  Boston  Soc.  Natural  His- 
tory, VII,  288.) 

§  120.  lieverting  now  to  Prof.  Adams,  we  tind  that  he  had 
already,  in  1840,  in  his  communication  just  cited,  advanced 
similar  views  to  those  of  Hitchcock.  The  strata  of  the  Lower 
Taconic  series  of  Emmons  occur,  in  Verinont,  to  the  east  of  the 
rocks  just  described,  and  between  them  and  the  Green  Moun- 
tains ;  and  A  dams  conceived  it  probable  that  "the  Taconic  quartz- 
rock  is  a  nietamorpbic  equ.valeut  of  the  Red  sand  rock."  In  a 
section  from  Lake  ("hamplain  to  the  Green  Mountains,  through 
Kerrisburg  and  Alonkton.^  there  seemed  to  bo  a  gradual  change 
in  lithological  cliaracters,  from  the  Red  sandrock  to  the  quartz- 
rock,  wiiich  he  ascribed  loathe  effect  of  ig-eous  agency 
in  the  eastern  part  of  the  section."  Inasmuch  as  the  section 
was  in  large  part  concealed,  however,  "  the  identity  of  the  Ta- 


ADAMS   ON   TACONIC    ROCKS. 


E.    61 


conic  quartz  rocks  with  the   Medina  sandstone  was  not  posi- 
tively affirmed." 

§  121.  A  similar  agency,  according  to  Adams,  might  also  have 
changed  tlie  limestones  which  overlie  the  Red  sandrock ; 
and  ill  sujiport  of  this  view,  a  section  from  Buck  Moun- 
tain, through  Waltham,  into  New  Haven,  was  exhibited, 
to  show  it  "somewhat  iirohable  that  the  Stockhridge  limestone 
of  the  Taconic  system  is  the  eciuivalont  uf  the  calcareous  rocks 
which  overlie  the  Red  sandrock,  rather  than  of  the  lower  lime- 
stones of  the  Cluiraplain  division,  as  luus  been  commonly  su{v 
posed."  (Amer.  Jour.  Science,  [2]  V,  page  108.)  The  al- 
lusion in  this  sentence  is  to  the  view  of  Mather,  already  ex- 
plained, (§  68)  which  had  at  that  time  ...en  accepted  by  James 
Hall,  II.  D.  Rogers,  W.  B.  Rogers  and  other  American  ge- 
ologists ;  who,  almost  without  exception,  rejected  the  Taconic 
system  of  Emmons,  and  regarded  the  Stockbridgc  limestone  as 
occupying  a  [)osition  between  the  Potsdam  sandstone  and  the 
Hudson  River  (Loraine)  shales. 

§  J  22.  The  comnmnication  of  Adams,  above  examined,  em- 
braced two  distinct  propositions:  first,  that  of  the  Levant  (or 
Medina)  age  of  the  Red  sandrock  and  its  overlying  limestones, 
(subsequently  included  in  the  Up{>cr  Taconic) ;  and,  second,  that 
of  the  conversion  of  this  series,  by  igneous  agency,  into  the 
granular  quartz-rock  and  the  granular  limestone  of  the  Lower 
Taconic,  and  the  consei^uent  Levant  age  of  these  latter.  The  sec- 
ond proposition,  although  accepted  by  Hitchcock  in  1860,  does 
not  appear  to  have  been  supporteil  by  Rogers. 

§  123.  We  have  seen  that  Mather  regarded  the  crystalline 
strata  of  southeastern  New  York  as  altered  or  Metamorphic 
rocks  of  the  Charaplain  division,  (§§  81-82,)  and  that  he  ex- 
tended this  view  to  the  similar  rocks  of  western  New  Eng- 
land, with  which  they  are  continuous.  These  gneisses  and 
crystalline  schists,  which  constitute  the  lower  division  of  the 
Primitive  series  of  'JJaton,  and  were  called  I'rimary  by  Em- 
mons, can  be  traced  over  the  greater  part  ol  New  England,  and 
form  the  chief  portion  both  of  the  Green  and  the  White 
Mountains.  Eaton,  although  familiar  with  the  rocks  of  west- 
ern New  England,  does  not  appear  to  have  studied  those  of 
the  White  Mountains,  nor  liad   they  attracted  the  attention  ot 


62  E. 


SPECIAL   REPORT.      T.  STERRT  HUNT,  1875. 


V 


Mather.  In  1844,  Messrs  H.  D.  and  W.  B.  Rogers,  in  an  essay 
upon  tlieir  geology,  state  that  these  mountains  had  previously 
been  regarded  as  belonging  to  the  "so-calleci  primary  periods  of 
geological  time."  They  however  extended  to  them  the  no- 
tions of  Mather,  and  suggested  that  the  crystalline  rocks  of  the 
region  were  altered  paleozoic  strata,  possibly  of  the  Matinal  di- 
vision, (Utica  i'-'^-^  Loraine,)  but  more  probably  belonging  to 
the  Levant  division,  which  included  the  Oneida,  Medina  and 
Clinton  formations  of  New  York.  The  gneisses  bore,  in  the 
opinion  of  these  observers,  some  resemblance  to  the  sandstones 
of  the  lower  part  of  this  division,  and  they  also  found,  in  cer- 
tain beds  among  them  forms,  which  were  conceived  to  be  the 
remains  of  crustaceans  and  brachiopods,  of  species  belonging 
to  the  Clinton  formation.  (American  Journal  of  Science,  [-)!, 
411).  .  In  1847,  (Ibid,  V,  HO,)  the  same  observers  announced 
that  they  no  longer  regarded  these  forms  as  of  organic  origin, 
but  did  not,  however,  retract  their  previously  expressed  opinion 
that  the  crystalline  stratified  rocks  of  the  White  Mountains  are 
of  paleozoic  age. 

§  124.  Charles  T.  Jackson,  to  whose  labors  the  geology  of 
New  England  is  much  indebted,  published  in  184L),  his  report 
on  a  geological  survey  of  New  Hampshire,  in  which  he  main- 
tained, (in  op])ositi()n  to  the  opinion  of  tiie  MessiJ.  Kogers,) 
that  the  White  Mountain^  constitute  an  axis  of  Primary  rocks, 
granite,  gneiss  and  mica-schist,  successively  overlaid,  both  to 
the  east  and  the  west,  by  Cambrian  and  Silurian  rocks.  These, 
on  the  western  side  of  the  axis,  in  Vermont,  have,,  according 
to  him,  been  changed  by  the  action  of  intrusive  serpentines, 
and  intrusive  qnartzites,  which  altered  the  Cambrian  strata  into 
the  gneissic  rocka  of  the  Green  Mountains,  and  converted  a 
portion  of  the  fossiliferous  limestones  of  the  Cl.aiiiplain  val- 
ley into  white  marbles — the  Lower  Tacouic  limestones  of  Em- 
mons. (Loc.  cit.,  pages  160-lil2). 

In  the  next  chapter  it  is  proposed  to  trace  the  history  of 
geological  investigation  in  Canada. 


CHAPTER  III. 


mSTORTCAIi    SKETCH,  CONTINUED. 

§  125.  Ilavint::;  given  in  the  preceding  cluipter  the  history 
of  geological  investigation  during  the  first  half  of  this  century, 
so  far  as  regards  the  ancient  rocks  under  discussion,  from  Vir- 
ginia northward  to  the  confines  of  Canada,  we  now  proceed  to 
a  consideration  of  the  lahors  of  the  (leological  Survey  of  that 
country,  the  ofllcers  of  which  have  continued  the  work  of  the 
ArnH. lean  geologists  already  mentioned,  and  have  greatly  ad- 
vanced our  knowledge  of  these  rocks.  In  this  connection, 
also,  will  he  discussed  the  geology  of  Lake  Superior. 

We  liave  already  seen  (§  ol)  that  Eaton,  as  early  as  1832, 
had  recognized  the  existence  of  gneissic  rocks  like  those  of 
the  Adirondack  Mountains,  extending  from  that  region  to  the 
vicinity  of  Alontreal,  and  also  to  Lake  Huron  and  Lake  Sujie- 
rior.  We  find,  moreover,  that  Emmons,  in  1842,  liad  traced 
the  rocks  of  the  Champlain  division  from  the  valley  of  the 
lake  of  this  name  to  Montreal  and  Quehec.  The  early  work 
of  Baddeley,  Bigsl>y  and  Bayfield  in  Canadian  geology  de- 
serves honorahle  mention  in  this  connection,  and  the  observa- 
tions of  the  latter  two,  so  tar  as  Ihey  bear  u})on  the  ques- 
tions before  us,  will  be  noticed  farther  on  in  the  chapter. 

[E.— ()3] 


64  E 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


§  120.  The  Geological  Survey  of  Canada  was  organized  in 
1842,  at  which  time  Mr.  (afterwards  Sir)  William  Edmund  Lo- 
gan was  appointed  cliicf  geologist,  and  Mr.  Alexander  Murray 
his  assistant.  The  views  of  Jjogan  on  the  geology  of  Canada 
at  that  time  are  emhodied  in  an  olHcial  letter,  accom[)anied  by 
a  preliminary  report,  dated  December,  1842.  These,  however, 
wore  not  [)ublished  until  1845,  when  they  appeared,  with  some 
explanatory  foot-notes,  in  a  volume,  together  wnth  the  report 
of  the  labors  of  Messrs.  Eogan  and  Murray  for  the  year  1843, 

§  127.  In  the  letter,  and  the  preliminary  report  just  alluded 
to,  Logan  distinguishes  a  series  of  'Trimary  and  Granite 
rocks."  elsewhere  described  as  "  a  range  of  syenitic  hills  of  a 
gneissic  order,"  bordering  the  St.  Lawrence  on  the  north,  and 
connected  by  "the  very  narrow  isthmus  of  the  Thousand  Is- 
lands "  with  the  siniilar  rocks  in  northern  Xew  York.  To  the 
westward,  these  Primary  rocks  were  said  to  form  the  northern 
shores  of  Lakes  Huron  and  Superior,  and  to  stretch  along  the 
north  side  of  a  great  basin  of  "  Transition  rocks,"  chieily 
limestones,  occupying  the  St.  Jjawrence  valley.  Logan  farther 
tells  us,  that  from  beneath  the  southern  edge  of  the  Transition 
trough,  "there  rises  an  important  formation  of  pyritiferoua 
clay-slate,  *  *  which  is  widely  spread  over  the  East- 
ern Townships,  south  of  the  St.  Lawrence."  In  the  foot-notes 
to  this  preliminary  statement,  it  was  however  said  that  these 
clay-slates  were  supposed,  from  farther  investigations,  to  be  of 
more  recent  origin  than  the  Transition  limestone,  and  "  pro- 
bably above,  instead  of  below  it,  in  geological  position."  Over- 
lying these  clay -slates  were  roticed  fossiliferous  limestones  of 
unknown  age,  found  on  the  river  Famine,  a  tributary  of  the 
Chaudiere,  and  on  the  river  St.  Francis,  near  Sherbrooke. 

§  128.  Referring  to  the  contorted  rocks  of  Point  Levis,  op- 
posite to  Quebec,  Logan  was  "  inclined  to  the  opinion  that  they 
come  out  from  below  the  flat  limestones  of  the  St.  Lawrence," 
though  he  added  in  a  foot-note  at  the  time  of  publication,  (in 
1845)  ihat  "the  accunmlation  of  evidence  points  to  the  con- 
clusion that  the  Point  Levi&  rocks  are  sujierior  to  the  St  Law- 
rence limestone."  In  this  latter  view  of  these  rocks  near  Que- 
bec, he  had  accepted  the  conclusions  of  Emmons,  announced  in 
his  report  published  in  1842  (§  65);  while,  as  regards  the  clay- 


PRIMARY    ROCKS    IN    CANADA. 


E.    65 


Blatc  formation, — supposed  by  Logan  to  be  a  prolongation  of 
tbe  Argillite  formation  of  Eaton  i'rom  eastern  New  York  and 
Vermont, — be  adopted  tlie  opinion  expressed  by  Matber  in  bis 
report  of  1843  (§  68). 

§  129.  Tbe  publisbed  results  of  tbe  geologists  of  New  York 
and  rennsylvania  were  at  tbis  date  familiar  to  Logan,  as  is 
made  more  evident  in  tbe  first  portion  of  bis  report  of  progress 
for  1843,  publisbed  witb  tbe  i)rt'ceding,  in  1845.  In  tbis  he 
describes  tbe  various  members  of  tbe  New  York  series  as 
traced  nortbward  tbrougb  tliese  States  into  tlie  great  Transi- 
tion trougb  of  tbe  St.  Lawrence,  and  remarks  tbat  "tbese  fos- 
sil iferous  formations,  wberevor  tbey  bave  lieen  found  in  actual 
contact  witb  tbe  rocks  beneatb,  appear  to  rest  upon  masses  of 
tbe  Primary  order.  But  the  geologists  of  New  York  consider 
tbat  tbey  bave  evidence  of  tbe  existence  of  a  series  of  non- 
fossiliferous  sedimentary  strata,  in  a  more  or  less  bigbi}'  crystal- 
line condition,  of  an  age  between  tbe  two."  Tbis  referred  to 
tbe  Taconic  system  of  Emmons,  already  at  tbat  time  announced 
by  bim  as  occupying  an  intermediate  position  between  tbe 
I'rimary  and  tbe  fossiliferous  rocks  of  the  New  York  series 
(§  67).  Logan,  however,  proposed  on  account  of  "tbe  consid- 
erable dilHculties  attending  tbe  question,  *  *  *  *  to 
unite  all  tbe  subjacent  rocks,  whether  Metamorpbic  or  Primary, 
and  to  class  them  under  tbe  latter  denomination." 

§  130.  Mr.  Murray,  in  bis  re[»ort  of  progress  for  1843,  jiub- 
lisbed  in  tbe  volume  just  mentioned,  noticed  tbat  some  of  tbe 
Primary  rocks  on  tbe  northeast  shore  of  Lake  Huron,  and  far- 
ther eastward,  north  of  Lake  Simcoe,  j (resent  evidences  of 
bedding  or  stratification,  Avbich  led  him  to  "consider  tbe  term 
Metamorpbic  as  one  of  appropriate  application  to  some  of  the 
rocks  beneath  the  fossiliferous, and  unconformable  with  them." 
He  therefore  designated  this  series  (described  by  bim  as  simi- 
lar to  those  of  tbe  Thousand  Islands)  as  "Primary  and  Meta 
niorphic  nu^ks." 

§  131.  In  tbe  year  1845,  Mr.  Logaii  ascended  the  Ottawa 
river  a  distance  of  150  miles  from  its  mouth,  to  tbe  bead  of 
Lake  Temiscaming,  exploring,  moreover,  some  of  its  tribu- 
taries, and  caretully  studied  the  geology  of  the  region,  niakiDg 


5- 


-E. 


m 


66  E. 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


large  collections.  In  the  followiiis^^  year  (18+0)  he,  with  the 
aid  of  Mr.  Murray,  exiihtred  in  like  manner  the  Canadian 
shores  of  Lake  Superior.  The  lahors  of  these  two  yeare  oon- 
trii)uted  ^n'eatly  to  our  knowledge  of  the  older  rocks,  but  the 
report.H  of  iheni  were  not  published,  nor  indeed  completed,  un- 
til 1847. 

§  132.  In  this  connection  a  personal  statement  may  perhaps 
be  permitted,  as  serving  to  give  weight  and  authenticity  to  the 
earlier  lithological  and  mineralogical  descriptions  in  these,  and 
in  subs('f|uent  reports  of  the  Canada  Survey,  which  have  a  his- 
torical importance  in  connection  with  the  study  of  the  older 
rocks.  It  was  in  February,  1847,  that  the  present  writer  com- 
menced his  lal)ors  at  Montreal,  as  chemist  and  mineralogist  to 
the  Geological  Survey  of  Canada  (after  having  previously,  for 
some  months,  tilled  the  same  post  in  the  Geological  Survey  of 
Vermont,  then  in  progress  under  Prof.  C.  B.  Adams).  The 
publication  of  the  re])oriS  of  the  Canada  survey  for  1845,  hav- 
ing been  delayed,  he  was  thus  enabled  to  examine  and  describe 
the  various  rocks  and  minerals  frojn  the  region  of  the  Ottawa, 
as  well  as  those  from  Lake  Superior.  For  the  lithological  and 
mineralogical  notes  and  descriptions  which  occur  in  the  reports 
for  1845  and  1840,  and  in  the  subsequent  publications  of  the 
survey,  during  twenty-five  years,  the  present  writer  is  respon- 
sible, inas(nuch  as  they  were  all  written  by  him  or  under  his 
supervision. 

§  133.  In  Logan's  report  on  the  geology  of  the  Ottawa,  im\)- 
lished  in  1847,  the  ancient  crystalline  rocks,  which  he  had  pre- 
viously called  Primary,  were  distinguished,  in  accordance  with 
Mr.  Murray's  previous  suggestion,  (§130)  as  "belonging'  to 
the  order  which,  in  the  nomenclature  of  Lyell,  is  called  Meta- 
niorphic  instead  of  Primary,  and  as  possessing  an  aspect  ind  ucing 
a  thecn'ctic  belief  that  they  may  be  ancient  sedimentary  foruia- 
tions  in  an  altered  condition.''  This  "■  Metanior[)hic  series" 
was  then  described  as  consisting  of  a  lower  and  an  upper  group, 
the  former  consisting  chiefly  of  reddish  and  grayish  syenitic 
(that  is  hornblendic)  gneisses,  much  contorted  and  generally  at 
high  angles.  These  were  succeeded  by  a  series  in  which,  it  was 
said,  "  im[>ortant  beds  of  crystalline  limestone  become  inter 
stratified  with  the  syenitic  gneiss,  and  their  presence  constitutes 


ROCKS  OF  THE  UPPER  OTTAWA, 


E.  67 


i() 


Ro  marked  a  eliaracter  that  it  ai>i)ears  exj»edient  to  coji.^iflerthe 
mass  to  which  they  hehmg  as  a  separate  group  of  metaniorplnc 
strata,  supposed,  from  their  geographieal  position  and  general 
attitude,  to  overlie  the  previous  roeks  conformahly." 

§  134.  A  careful  section  of  a  portion  of  this  "  upper  grou]>," 
as  it  was  then  called,  was  given,  aceom[)anied  by  minute  litho- 
logical  descriptions  of  the  gneisses  of  both  groups,  and  of  the 
crystalline  limestones,  together  with  the  minerals  botli  of  the 
strata  and  the  numerous  veinstones  occurring  in  them  ; — the 
results  of  a  careful  study  by  the  present  writer  of  the  collec- 
tions made  in  !845.  (Report  for  1845,  pp.  40-50.)  In  1.^47  he 
spent  some  weeks  in  the  field  among  the  saine  rocks,  and  his 
report  thereon  will  be  found  to  contain  farther  details  ol'  their 
mineralogy  and  lithology  (Report  for  1848,  pp.  125-138). 

§  '35.  This  Mctamorphic  series,  of  two  conformable  groups, 
was  described  l)y  Logan  in  1845,  as  forming  a  great  axis,  cross- 
ing the  Ottawa  river,  and  separating  the  rocks  of  the  southern 
trough  of  fossiliferous  rocks,  (the  great  Transition  ti-ough  of 
the  St.  Lawrence  and  the  lower  Ottawa,  already  noticed)  from 
a  northern  trough,  the  strata  of  which  was  discovered  by  him 
on  Lake  Temiscaming,  on  the  upper  Ottawa,  resting  upon  the 
Metamorphic  series.  They  were  then  described  as  consisting, 
in  ascending  order,  of  l°,.chloritic  slates  and  conglomerates;  2", 
greenish  sandstones  ;  3°,  fossiliferous  limestones.  The  first  of 
these  were  grayish  and  greenish  slates,  chloritic  or  finely  mica- 
ceous, often  very  compact,  traversed  l»y  sean>s  of  quartz,  and 
sometimes  holding  pebbles  and  rounded  masses  of  the  subjacent 
gneiss.  These  strata  had  a  moderate  diji,  and  an  estimated 
thickness  of  not  less  than  1,000  feet.  Reposing  on  these  slates 
were  Rcveral  luuidred  feet  oi'  greenish  sandstones  and  conglom- 
erates, in  neai'ly  horizontal  beds,  overlaid  by  400  or  500  feet  of 
light  gray  limestones,  sometimes  abounding  in  chert  and  inter- 
stratified  with  gret'uish  shales.  Many  of  the  limestones  were 
very  fossiliferous,  containing  the  characteristic  organic  forms 
of  the  Niagara  limestone.  A  conglomerate,  made  up  of  the 
ruins  of  the  underlying  sandstone,  formed  the  base  of  the  lime- 
stone series. 

§  136.  In  the  following  year  (1846)  the  work  of  Logan  and 
of  Murray  on  Lake  Superior  and  its   tributaries,  added  much 


G8  E. 


SPKCIAL  BEPOKT.       T.  STEKKV    HUNT,  1875. 


more  to  our  knowledijce  of  the  older  mcks.  In  liif^  roi)ort,  pul)- 
lislied  in  1847,  tlie  former  described  tlie  Icnvest  rock.s  aUniL!;  the 
north  shore  of  the  luke  as  consisting  of  granite  and  syenitic 
(hornblendicj  granite,  "  which  ai)pear  to  jtass  gradually  into 
gneiss."  Siniihir  rocks  were  also  observed  by  Murray  in  the 
Kanianistiquia  and  Michipicoten  rivers,  liesting  u[ion  these 
ancient  rocks,  and  in  many  places  enclosing  jiebbles  of  them, 
was  u  second  series,  described  as  consisting  of  chloritic,  miea- 
ceons  and  talcose  slates,  sometimes  epidotic,  with  interstratitied 
beds  having  the  characters  of  greenstone,  and  others  of  ([U.irtz- 
rock,  the  whole  series  iinich  contorted,  and  dijiping  at  high 
angles,  with  an  oast  and  west  strike.  Tln'ir  thickness  was  esti- 
mated at  several  thousand  feet,  and  they  were  observed  by  Lo- 
gan at  the  moutb  of  the  river  Dore  near  (ires  Cap,  and  at 
Tiiunder  Bay,  and  also,  by  Murray,  on  the  Kanianistiquia. 
The  former  declared  that  the  "chloritic  slates  at  the  summit 
of  the  older  rocks,  upon  which  the  Volcanic  formations  rest  un- 
confomial)ly,  strongly  rcsend)le  those  of  Lake  Temiscaming, 
and  it  appears  prol)able  that  they  will  be  found  to  be  identical" 
with  ttiem.     (Report  for  1840,  page  34.) 

§  137.  The  "Volcanic  formations," above  alluded  to,  are  de- 
scribed by  Logan,  in  the  same  report,  as  consisting  of  uncrystal- 
line  sedimentary  iitrata,  interstratified  with  and  overlaid  by 
eruptive  rocks,  and  were  divided  by  him  into  a  lower  and  upper 
group.  The  first  of  these  was  seen  at  Thunder  Bay,  resting,  in  a 
nearly  horizontal  jxisition,  ujion  the  highly-  inclined  chloritic 
slates,  fragments  of  which  entered  into  a  conglomerate  at  the 
base  of  the  lower  Volcanic  series. 

Overlying  this  conglomerate  were  beds  of  chert  orhornstone, 
with  calcareous  layers,  sometimes  becoming  impure  limestones; 
the  whole,  higher  in  the  series,  accom[)anied  with  dark  bluish 
argillaceous  slates  and  argillaceous  sandstones,  intersected  by 
dykes,  and  interstratitied  witii  layers  of  crystalline  hornblendic 
trap;  a  mass  of  which,  200  or  300  feet  in  thickness,  caps  the 
lower  group,  estimated  to  have  a  total  volume  of  1,500  or  2,000 
feet.  These  rocks  are  seen  at  Thunder  Bay  and  westward  to 
Pigeon  river,  forming  the  shores  of  the  lake  and  the  adjacent 
islands. 

§  138.  Resting  upon  this  lower  group  to  the  eastward,  was 


VOLCANIC    fOKMATIo.NS    OF    LAKE    Sl'l'KRIOK. 


E.    GO 


a  faeries  of  rod  aiul  vvliite  siindstoiK's,  iuid  CDiigloineratos,  lidld- 
ing  jiebblcs  of  Jjisper,  dieit  mid  liinesfone,  and  huviui;  an  esti- 
mated thickness  of  about  700  teot.  These  were  succeeded  \>y 
reddisli  white  conipaet  limestones,  interstratified  with  calcare- 
ous shales  and  sandstones,  and  overlaid  by  reddish  marls, mak- 
ing, in  all,  about  130  feet  additional.  "Succeeding  these  cal- 
caremis  strata,  alter  an  interval  of  which  the  amount  is  uncer- 
tain,'' another  series  of  red  and  white  sandstones,  with  con- 
glomerate layers,  was  met  with.  These  were  interstratilied 
with  layers  of  trap,  often  aniygdaloidal;  "and  an  enormous 
amount  of  volcanic  oveiHow  crowjis  the  formation."  Besides 
the  bedded  aniyg<laIoids  wei-c  great  masses  of  highly  crystalline 
trap,  [lassing  into  well-marked  basalt,  togetlicr  with  vitreous 
trajis  having  the  forms  of  {pitchstone  and  jiitchstone-i>orithyry. 

The  thickness  of  this  ui>i)er  Volcanic  group,  on  which  were  in- 
cluded the  calcareous  strataand  the  red  and  white  sandstones  be- 
neath them,  was  estimated,  as  seen  in  various  sections,  at  from 
(3,000  to  10,000  feet.     (Rei)ort  for  184(3,  pages  13-16). 

§139.  This  series  was  i'ound  to  the  east  of  Thimder  Bay,  rest- 
ing upon  the  rocks  of  the  lower  Volcanic  group  just  described, 
beyond  which  it  was  recou-nized  on  fSt.  lijnace  and  the  other  is- 
lands  along  Nipigon  Bay,  and,  liirther  east,  in  Michiiiicoten  Is- 
land, and  on  the  maiidand  at  Cajic  Gargantua,  J'ointo  aux 
Mines,  Mamairlse  and  other  places,  in  which  the  red  sandstones, 
conglomerates  and  amygdaloids  of  the  upper  Volcanic  group 
were  seen  to  lie  unconibrmably  upon  the  ancient  gneissic  and 
granitic  rocks.  This  sei'ies,  in  many  }>arts  of  its  distribution, 
abounds  in  native  copper,  and  was  by  Jjogan  regarded  as  iden- 
tical with  that  of  Isle  Koyale,  then  visited  by  him,  and  with 
the  similar  copper-bearing  rocks  of  the  southern  shore  of  Lake 
Superior.  As  regards  the  age  of  tlie  copper-bearing  series,  lie 
conceived  it  to  be  older  than  the  horizontal  j)aleozoic  sandstones 
found  in  the  vicinity  of  Sault  Ste.  Marie,  and  cited  with  ap- 
proval the  opinion  expressed  by  llaughton  of  Michigan,  in 
18-11,  that  it  was  probably  more  ancient  than  the  Potsdam  of 
the  New  York  series.  The  important  bearing  of  these  facts  on 
the  history  of  the  Lake  Superior  rocks  will  be  apparent  further 
on. 


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IMAGE  EVALUATION 
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Photographic 

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Corporation 


23  WEST  MAIN  STREET 

WEBSTER,  NY.  14580 

(716)  872-4503 


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&?^ 


70  E 


SPECIAL   REPORT.       T.  STERRY    HUXT,   1875. 


Ill 


§  140.  In  the  summer  of  1847,  Mr.  Alexander  Murray  com- 
menced the  geological  exploration  of  tiie  north  shore  of  Lake 
Huron,  where,  as  is  described  in  his  report  of  that  year,  he 
found,  resting  upon  granitic  and  gneissoid  rocks,  a  great  series  of 
chloritic  slates  and  conglomerates,  with  interstratified  green- 
stones, quartzites  and  limestones.  This  intermediate  series  was 
described  as  forming  the  whole  northern  shore  of  the  lake, 
and  as  unconformably  ov^erlaid  by  the  lower  members  of  the 
New  York  series  of  paleozoic  rocks. 

These  explorations  were  continued  by  Mr.  Murray  in  1848 
and  1849.  The  frequent  occurrence  of  suli)huretted  ores  of 
copi)er  having  been  noticed  in  tlic  intermediate  series  of  rocks, 
they  had  already  attracted  the  attention  of  mining  explorers, 
when,  in  1848,  the  region  was  also  visited  by  Mr.  Logan,  in 
company  with  the  present  writer. 

§  141.  The  reports  of  both  Murray  and  Logan  for  1848  con- 
tain much  additional  information  respecting  this  series  of 
rocks.  The  great  likeness  between  these  and  the  chloritic- 
slate  formation,  previously  examined  and  described  on  Lake 
Temiscaming  and  Lake  Superior,  is  however  nowhere  alluded 
to  in  these  reports,  though  their  identity  was  some  years  after- 
wards fully  recognized  in  the  official  publications  of  the  geo- 
logical survey.  In  explanation  of  this,  it  must  be  said  that 
Logan  conceived  these  co|,per-bearing  rocks  of  Lake  Huron, 
notwithstanding  their  lithological  dissimilarity,  to  be  the  geo- 
logical ecpii  valents  of  the  so-called  Volcanic  formations,  which  he 
had  previously  described  as  resting  unconformably  uiH)n  the 
similar  chloritic  slates  and  greenstones  of  Thunder  Bay  on  Lalte 
Superior. 

In  his  report  for  1848,  (page  '20,)  he  atteripts  to  compare  the 
copper-bearing  rocks  of  Lake  Huron  with  tuose  yielding  native 
copper  on  Lake  Superior.  The  greenstontis  of  the  former, — 
which  he  regarded,  in  accordance  with  the  vhen  universally  re- 
ceived view,  as  of  igneous  origin, — were  coiifc^ecdiy  unlike 
the  amygdaloida  of  Lake  Superior ;  and  the  sandstones  asso- 
ciated with  these  were  very  luilike  the  vitreous  quartzites 
which,  on  Lake  Huron,  w^re  interstratified  with  the  crystal- 
line greenstones  and  chloritic  slates  containing  thepyritouscop 
per    ores   of    that    region.     But,   in  his    language,  "notwith 


\y 


Va 


ROCKS   OF    LAKES    HURON    AND   SUPERIOR    COMPARED.    E.    71 


standing  these  ditt'erences,  there  are  such  strong  points  of  re- 
semblance, in  the  interstratification  of  igneous  rocks,  and  the 
general  mineralised  condition  of  the  whole,  as  to  render  their 
positive  or  approximate  equivalence  highly  probable,  if  not  al- 
most certain." 

§  142.  Much  stress  was  laid  by  him  upon  the  fact  these 
two  formations  were  found,  in  contiguous  regions, — ^thechloritic 
and  greenstone  series  on  the  north  shore  of  Lake  Huron,  ex- 
tending westward  nearly  to  Sault  Ste.  Marie,  and  the  amygda- 
loid series,  with  native  copper,  at  the  eastern  end  of  Lake  Su- 
perior,— both  resting  unconformably  upon  the  ancient  granitic 
series,  and  both  overlaid  conformably  by  the  newer  and  hori- 
zontal sandstones,  then  regarded  as  the  equivalent  of  tlie  Pots- 
dam of  the  New  York  sorie^*.  The  fact  that  the  amygdaloid 
series  further  west,  in  Thunder  Bay,  had  beneath  it  the  dark 
colored  argillites  and  sandstones,  which  in  tlieir  turn  rested 
unconformably  upon  a  chloritic  and  greenstone  series  like 
that  of  Lake  Huron,  was  strangely  overlooked.  That  the 
great  dift'erence  between  these  copper  bearing  rocks  on  the 
two  lakes  was,  in  some  way,  due  to  the  action  of  supposed  in- 
trusive rocks,  which  had  metamorphosed  the  one  more  highly 
than  the  other,  was  the  view  entertained  by  Logan  for  man}' 
years.  This  same  view  is  well  stated  by  Dr.  J.  W.  Dawson, 
who,  in  1857,  published  a  detailed  account  of  an  examination 
of  the  cupriferous  amygdaloidsand  conglomerates  of  Mamainse, 
and,  accepting  the  view  of  Logan,  (also  adoi)ted  by  llivot,) 
that  these  were  the  geological  equivalents  of  the  Lake  Hu- 
ron series,  ex[»ressed  the  opinion  that  while  these  latter 
"may  have  thus  originally  been  similar  to  those  of  Mamainse, 
they  have  been  far  more  altere<!,  and  are  associated  with 
the  deep-seated  crystalline  jiroducts  of  volcanic  agency,  in- 
stead of  with  those  that  are  superficial.  Differences  of  this 
kind  imply,  however,  no  difference  in  age."  Canadian  Natural- 
ist, vol.  II,  page  11). 

§  143.  Tine  observations  of  Mr.  Murray  on  Lake  Huron  liad 
already  shown  the  existence  of  two  unconformable  series  of 
crystalline  stratified  rocks,  which  were,  in  their  turn,  overlaid 
in  discordant  stratification  by  the  nearly  horizontal  paleozoic 
strata,  reposing  sometimes  on  the  older  and  sometimes  on  the 


72  E.      SPECIAL  REPORT.   T.  STERRY  HUNT,  1875. 


younger  of  the  crystalline  series.  The  former  of  these,  con- 
sisting of  granitic  and  gneissic  rocks,  with  crystalline  limestones 
interstratitied  in  the  upper  portion,  had  heen  distinguished  as 
the  Motamorpliic  series,  but  tliis  nan.  3  was  not  less  apjilicable 
to  the  overlying  group  of  chloritic  slates,  with  greenstones 
and  quurtzites.  It  was  therefore  proposed  to  give  the  older 
group  a  distinctive  name,  and  inasmuch  as  these  rocks  form 
the  hills  on  the  north  side  of  the  tSt.  Lawrence,  to  which  Mr. 
Garneau,  the  Canadian  historian,  had  already  given  the  geo- 
graphical name  of  Laurentiderf,  "the  distinctive  appellation 
of  Laurontian,"  proposed  by  the  present  writer,  was  applied 
to  them  in  the  Report  of  the  Geological  Survey  of  Canada  for 
1852,  (page  9,)  which  was  published  in  1851:. 

§  144.  In  the  next  year,  (1855)  tiiere  was  published  in 
Paris,  under  the  name  of  "  Esquisse  Geologique  du  Canada, 
par  W,  E.  Logan  and  T,  iSterr}'  Hunt,"  a  small  volume,  with  a 
geological  map,  intended  to  explain  the  geology  of  Canada  as 
then  presented  at  the  great  Exhibition  at  Paris. 

In  this  little  treatise  the  name  of  Laureutian  was  again  em- 
ployed to  designate  the  ancient  gneissic  series,  and  at  the  same 
time,  the  name  of  Iluronian  was  proposed  by  the  present  writer 
to  distinguish  the  younger  and  unconformable  series  of  crys- 
talline rocks  found  on  the  shores  of  Lake  Huron,  and,  also, 
the  so-called  Volcanic  formations  of  Lake  Superior,  tlien  con- 
sidered as  their  geological  equivalents.  Henceforth  the  terms 
Laurentian  and  Iluronian,  which  were  used  in  the  geological 
map  accompanying  the  little  volume,  were  employed  by  the 
Canadian  Survey,  and  have  since  been  generally  adopted  by 
geologists. 

§  145.  Of  those  Iluronian  rocks  it  was  then  said  that  they 
"may  be  referred  to  the  Lower  Cambrian  of  Sedgwick;"  inas- 
much as  I  was  then,  as  now,  of  the  opinion  that  these  rocks 
are  identical  with  those  crystalline  strata  in  Caernarvonshire 
and  Anglesea,  which  Sedgwick  had,  in  1835,  designated  as 
Lower  Cambrian,  and  which  Murchison  still,  in  1855,  errone- 
ously regarded  as  the  lower  part  of  the  proper  Cambrian  series 
in  an  altered  condition.  (Hunt,  Cheni.  and  Geol.  Essays, 
pages  353,  383.)  Sedgwick  had  long  previous  to  this  placed 
these  crystalline  rocks  at  a  horizon  below  the  base  of  the  Cam- 


A 


FOSTKR    AND   WHITNEY    ON    LAKE   SUPERIOR. 


E.  73 


brian,  but  the  authority  of  Murchison  was,  in  1855,  unques- 
tioned. Dr.  Bigsby,  in  I8G0,  insisted  that  the  typical  Iluronian 
rocks  on  Lake  Huron,  witli  which  he  had  long  before  been  fa- 
miliar, were  in  no  way  to  be  confounded  with  the  typical  Cam- 
brian of  Wales,  but  beloncjed  to  a  more  ancient  series.  (Ibid, 
page  269,  and  Quar.  Jour.  Gcol.  Society,  XIX,  3(3.) 

§  140.  Meanwhile  had  ai)peared,in  1851,  the  elaborate  report 
of  Messrs  J.  \V.  Foster  and  J.  D.  Whitney,  on  the  geology  of 
portions  of  Lake  Superior,  including  the  south  shore  and  Islo 
Royale.  This  was,  up  to  that  time,  the  most  important  and 
considerable  contribution  which  had  been  made  by  the  geology 
of  our  older  rocks,  Prof.  Whitney  having  brought  to  the  sub- 
ject a  wide  acquaintance  with  the  literature  of  geology  and 
mineralogy.  We  give  below  his  grouping  and  nomenclature 
of  the  rock-masses  of  the  Lake  Superior  region,  in  accordance 
with  the  classification  of  Constant-l'revost.  (Geology  of  Lake 
Superior,  vol.  II,  page  2). 


I 

■A- 


I.  Igneous  ;  of  various  af^es,  divided  into 

A.  Plutonic  rocks;  ooiisisting  of  ({ranite,  Syenite;  and 
Feldspar  and  Quart7».rock. 

B.  Trappoan  and  Volcanic  rocks ;  consisting?  of  Greenstono 
or  Dolorite  ;  Porpliyry  ;  Hasjilt;  Am}'ji;(lal()id  ;  Horn- 
blende and  Serpentine  rooks;  musses  of  Specular  and 
Magnetic  Oxyds  of  Iron. 

II.  Metamorphio  ;  belonging  to  the  Azoic  sysfcm,  including 

Gneiss;  Mica  and  Hornblende  Slate;  Chloritti, Talcose, 
and  Argillaceous  Slate;  beds  of  Quartz  and  S&ccba- 
roidal  Marble. 

III.  Aqueous;  beginning  with  Lower  <V</Mrtan, of  wliich  the 

members  were,  in  asi'ending  order:  Potsdam  siiiid- 
stone ;  (laloiferous  sandrock;  t'liazy  limestone;  fol- 
lowed by  the  Trenton  limostone,  with  its  subdivisions  ; 
the  Utica  slate,  and  the  Loraino  or  Hudson  liiver  slates 
of  the  New  York  series.     (§  64.) 


Besides  these  three  great  classes  there  are  included,  under  the 
name  of  Pluto-Neptunian,  those  volcanic  rocks  which  have 
been  modified  by  water  after  their  ejection,  and  therel>y  arranged 
in  stratified  deposits,  such  astrap-tulf  and  i)eperino,  which  wore 
su})posed  to  bo  largely  represented  in  the  copper-bearing  for- 
mation of  Lake  Superior. 


rm 


74  E. 


SPECIAL  REPORT.      T.  STERRY    HUNT,  1875. 


§  147.  Includiuo;  the  specular  and  magnetic  iron  ores  of  Lake 
Superior  (and  of  other  regions)  among  the  igneous  rocks,  the 
authors  discuss  the  view  tiiat  they  were  deposited  from  water, 
which  is  declared  to  be  inadmissible  and  inadequate  to  explain 
the  geological  relations  of  these  ores.  Nothwithstanding  the 
banded  structure  of  these  deposits,  as  seen  on  Lake  Superior, 
they  were  "  disposed  to  regard  the  specular  and  magnetic 
oxyds  of  iron  as  a  purely  igneous  product,  in  some  cases  poured 
out,  but  in  other  cases  sublimed  t'vom  the  interior  of  the  earth." 
Many  of  the  deposits  of  pure  ore,  enclosed  in  crystalline  strata, 
or  traversing  such  in  dykes,  are  supposed  to  "  have  risen  up  in 
a  plastic  state  from  below  ;"  but  when  found  impregnating  crys- 
talline strata,  or  interlaminated  with  them,  their  introduction 
was  regarded  as  due  to  sublimation.  The  banded  structure  of 
the  masses  of  ore,  and  its  iuterlamination  with  chert,  jasper  and 
other  matters,  suggesting  aqueous  deposition,  they  supposed 
to  be  due  "  to  the  action  of  segregating  forces."  (Geology  of 
Lake  Superior,  II,  68.) 

§  148.  The  Azoic  system,  as  defined  by  Foster  and  Whitney, 
included  both  the  older  gneissic  or  Metaniorphic  series  of  the 
Canada  survey  (subsequently  named  Laurentian,)and  the  newer 
and  unconformable  crystalline  aeries  afterwards  called  IIu- 
ronian.  This,  as  developed  on  the  southern  shore  of  Lake  Su- 
perior, included  besides  chloritic  and  talcose  schists,  the  great 
deposits  of  iron  ores  just  referred  to,  masses  of  greenstone,  to- 
getiier  with  dark  colored  compact  serpentines,  and  quartzifer- 
ous  porphyries  ;  all  of  which  were  regarded  as  being  of  igne- 
ous origin,  and  as  intercalated  in  the  metamorphic  schists  of 
the  Azoic  system. 

The  copper-bearing  series  of  tlie  region,  including  the  amyg- 
daloids,  inter-bedded  traps,  and  conglomerates,  was  however  re- 
ferred to  a  more  recent  period,  being  regarded  as  forming  a  por- 
tion of  the  Totsdam  siindstone. 

§  149.  An  instructive  section  given  by  Foster  and  Whitney 
(Vol.  I,  page  OG)  near  the  eastern  end  of  Keweenaw  Point,  from 
Copper  Harbor  southward  to  Lake  Labelle,  traverses,  in  the 
northern  portion,  two  principal  ranges  of  bedded  amygdaloid 
and  granular  trap  with  conglomerates  and  native  cojtper.  To 
the  south  of  this,  a  third  parallel  cast  and  west  belt  of  so-called 


JASPER    AND   QUARTZOSE    PORPHYRY    KoriCS. 


E.  75 


••iiii 

'I 


trap,  constitutes  the  Bohemian  Mountains,  descrihed  as  com- 
posed of  "  a  vast  crystalline  mass,  forming  an  anticlinal  axis, 
flanked  on  the  north  hy  the  bedded  traps  and  conglomerates, 
and  on  the  south  by  sandstones  with  conglomerates  "  'J'his 
southern  range  is  said  tube  widely  utdikeboth  in  structure  and 
composition  to  the  traps  of  the  northern  ranges,  being  a  dark- 
colored  tine-grained  greenstone,  made  up  of  labradorite  and 
green  hornblende,  sometimes  with  an  admixture  of  chlorite. 
It  is  distinctly  stratified,  and  di])s  to  the  N.  W.  at  an  angle  of 
65°  or  70°.  At  the  southern  base  of  the  range  is  a  broad  belt 
of  fissile  chloritic  rock,  which  is,  in  parts,  an  admixture  of 
labradorite  and  felds})ar,  with  disseminated  crystals  of  mag- 
netite and  grains  of  copi)er-pyrites. 

§  150.  Throughout  this  southern  range  native  copper  is  want- 
ing, but  numerous  veins  of  quartz,  sometimes  with  calcite  and 
chlorite,  are  met  with,  carrying  sulphurerted  copjier  ores.  In 
the  eastern  part  of  the  Bohemian  range  (according  to  Ri'  ot) 
the  greenstone  is  replaced  by  a  jasper,  which  forms  great  masses, 
and  makes  the  sunnnit  of  Mount  Houghton.  This  rock  is  sup- 
posed by  Foster  and  Whiniey  to  have  resulted  from  the  altera- 
tion, by  the  intrusive  traj),  of  the  adjacent  sandstones,  and  is 
described  as  in  some  parts  red,  occasionally  banded  and  com- 
pact, with  a  sub-conchoidal  fracture ;  elsewhere  it  includes  feld- 
spar and  chlorite,  and  shows  lines  of  stratification. 

§  151.  A  similar  red  bandinl  jasper-rock  occurs  in  the  Por- 
cupine Mountains,  a  range  of  hills  near  the  southern  shore  of 
the  lake,  rising  between  Carp  and  Iron  rivers,  where  a  large 
area,  designated  in  the  geological  map  of  Foster  and  Whitney, 
as  composed  of  "  igneous  "  rocks,  is  described  by  them  as  con- 
sisting of  Jasper  and  quartzose  porphyry.  The  highest  parts 
of  these  hills  are  said  to  be  composed  of  a  compact  red  jasper, 
sometimes  banded,  and  at  other  times  mingled  with  grains  of 
white  quartz.  It  "sometinjes  shows  a  gra(iual  passage  into 
quartzose  porphyry,  with  occasional  imbedded  crystals  of  felds- 
par." Such  a  porphyry  forms  very  large  masses  on  the  head- 
waters of  Iron  river,  where  it  is  brick-red  in  color,  and  con- 
tains small  crystals  of  white  feldspar,  generally  with  "  rounded 
grains  of  vitreous  qiuxrtz  found  distril)uted  with  the  feldspar 
through  the  jasper  base."     Other  varieties  are  described  with 


76  E. 


SPECIAL   REPORT.      T.  STERRY    HUNT,  1875. 


i      I 


I        !! 


rod  feldspar  crystals.  This  rock  was  regarded  by  the  authors 
as  an  eruptive  mass,  and  said  to  include  fragments  of  older 
rocks.  (Geology  of  Lake  Superior,  I,  65-70).  The  banded 
structure  of  some  of  the  jasper  of  Mount  Houghton  was  re- 
garded bv  them  as  due  to  the  original  stratification  of  the  sedi- 
mentary  deposits,  while  that  of  the  banded  jaspci  if  the  Por- 
cupine Mountains  was  declared  (Ibid.  II,  68)  to  present  com- 
plex flexures,  which  "  bear  no  mark  of  having  been  the  re- 
sult of  original  stratification  ;"  there  being  no  actual  line  of 
separation  between  the  lighter  and  darker  bands.  We  shall 
again  refer  to  these  jaspers  and  porphyries. 

§  152.  In  1854,  and  again  in  1855,  Prof.  Rivot,  of  the  Ecole 
des  Mines  of  Paris,  visited  the  mining-region  of  Lake  Su- 
perior, and  described  his  observations  in  two  elaborate  memoirs 
in  the  Annales  des  Mines  for  1855  and  1856  (5me.  serie,  vols.  V 
and  X).  We  have  already  made  use  of  his  statements  in 
speaking  of  the  Bohemian  Moun+ains.  Rivot  recognized  in 
this  region,  besides  the  ancient  granitic  and  syenitic  rocks, 
which  he  regai'ded  as  eruptive,  a  vast  series  of  chloritic  and 
hornblendic  schistose  rocks,  which,  according  to  him,  pass  by 
insensible  gradations  into  the  massive  greenstones  found  inter- 
stratified  with  them.  Hence  he  rejected  entirely  the  notion 
of  the  igneous  origin  of  the  greenstones,  described  by  him  as 
consisting  chiefly  of  labradorite  and  hornblende,  which  were 
conspicuous  in  the  hills  of  the  Bohemian  range  already  no- 
ticed, as  well  as  in  the  Huron  Mountains  and  near  Marquette. 
The  cupriferous  aiuygdaloids  and  bedded  traps  of  the  more 
northern  ranges  in  the  Keweenaw  peninsula  were  supposed  by 
Rivot  to  belong  to  the  same  series  as  the  greenstones  found 
with  the  chloritic  and  hornblendic  schists  mentioned  above, 
and  to  pass  into  them  by  gradations. 

§  153.  Rivot  thus  rejected  entirely  the  notion  of  the  erup- 
tive or  volcanic  origin  of  the  amygdaloids  and  bedded  trai>s  of 
the  cupriferous  formation,  maintaining  that  they  were  of  meta- 
morphic  origin,  and  in  fact  that  these,  as  well  as  the  whole  se- 
ries ot  greenstones  with  chloritic  and  hornblendic  slates,  ser- 
pentines, jaspers  and  iron  ores,  in  the  Huron  and  Bohemian 
Mountains,  had  resulted  from  the  more  or  less  complete  altera- 
tion of  ferruginous  slates  and   and   sandstones  "by  some   un- 


RIVOT    ON    LAKE   SUPERIOR. 


E.  77 


nul 

vo. 


known  agent."  The  whole  of  these  strata  were  by  him  sup- 
posed to  be  intercalated  in  the  lower  part  of  the  paleozoic  se- 
ries, and  he  did  not  apparently  recognize  any  disi-ordance  ot 
stratification  between  the  ])receding  rocks  and  the  superioi 
sandstones  of  the  region,  lie  noticed  that  in  the  greenstone 
and  chloritic  series  of  the  Bohemian  range  (and  elsewhere)  cop- 
per was  found  in  veins,  in  the  form  of  sulpiiuretted  ores,  but  ho 
believed  that  these  veins  were  in  some  cases  continuous  with 
those  which,  in  the  amygdaloid  belts  to  the  northward,  carried 
metallic  copper. 

§  154.  llivot  was  familiar  with  the  results  of  the  Canadian 
survey,  and  in  his  memoir  of  1856  gave  an  analysis  of  the 
Esquisse  Geolo()i(]ue,  already  mentioned,  citing  the  names  Lau- 
rent ian  and  lluronian.  lie  there  states  more  distinctly  than 
in  his  first  memoir  his  view  of  the  relations  of  the  various 
rocks,  and  declares  that  "in  immediate  contact,  and  apparently 
with  the  granite,  are  found  rocks  evidently  raetamorphic,  mica- 
schists,  hornblendic  sc-hists  very  analogous  to  traps,  <^uartzites 
and  jas^ters.  At  a  certain  distance,  and  above  these,  are  the) 
traps,  conglomerates  and  sandstones,  the  stratified  arrangement 
of  which  is  very  evident.  It  is  not  possible,  at  least  on  the 
American  shore,  to  separate  the  traps  from  the  other  Silurian  i  \ 
rocks."  On  the  other  hand,  he  describes  traps  as  passing  into 
well  characterized  raetamorphic  schists,  and  declares  them  to 
be  "so  connected  with  the  metamorphic  rocks,  referred  by  Mr. 
Logan  to  the  Cambrian  (lluronian),  that  it  is  not  possible  to 
separate  the  two.  These  appear  as  the  last  term  of  the  meta- 
morphic action  manifested  at  the  contact  of  the  granite,  of 
which  action  the  granite  itself  may  perhaps  represent  only  the 
highest  development."  The  discordance  noticed  by  Logan  at 
Thunder  Ba}'  between  the  crystalline  schists  and  the  overlying 
series  of  argillites  and  sandstones  with  traps,  Rivot  thought 
might  only  be  a  local  phenomenon,  "to  be  explained  by  move- 
ments due  to  the  neighberhood  of  the  granite." 

§  155.  The  granites  of  this  author  were  the  granitoid  rocks 
of  the  Laurentian  system,  which  he  elsewhere  described  as 
"important  masses  of  granite,  syenite  and  diorite,  which  seem 
to  have  traversed  and  disturbed"  the  more  schistose  lelds[)athic, 
micaceous  and  hornblendic  rocks,  and  the  crystalline  limestones 


m 


I  I 
i 


1  I 


78    E.  SPECIAL    REPORT.      T.  8TERRY    HUNT,  1875. 

of  the  Laiirentian.  In  the  bedded  trappean  rocks  of  the  cop- 
per bearing  series  he,  however,  failed  to  recognize  any  eru]*- 
tive  masses,  and  found  none  of  "the  dykes  of  trap  or  diorite" 
noticed  by  Logan  in  this  series  on  the  north  shore  of  tlie  lake. 
The  granites  and  related  rocks  seem  to  have  been  the  only 
masses  in  the  region  to  which  Rivot  assigned  a  phitonic  origin. 

§  156.  The  observation  of  Rivot  regarding  the  origin  of  the 
beds  of  rounded  pebbles  found  between  ridges  of  trap  at  Ke- 
weenaw Point  deserves  notice  in  this  connection.  They  were, 
according  to  him,  "due  to  the  decomposition,  by  atmospheric 
agents,  of  the  ancient  conglomerate."  The  present  writer,  from 
his  observations  on  the  north  shore  of  the  lake  in  1872,  arrived 
at  the  same  conclusion.  At  Mamainse,  interstratified  with  the 
traps,  are  beds  of  conglomerate  made  up  of  large  and  small 
rounded  masses  of  granite,  red  and  gray  Laurentian  gneiss, 
chloritic  schists  and  greenstones  from  the  Iluroniaii  series,  and 
tender  mica-schists  and  gneisses  having  all  the  characters  of 
the  Montalban,  together  with  masses  of  red  quartzose  sand- 
stone, the  whole  cemented  by  white  cleavable  calcareous  spar. 
The  solution  of  this  has  reduced  large  portions  of  the  con- 
glomerate to  loose  pebbles,  which  form  the  lake  shore. 

§  157.  It  thus  appears  that  Rivot,  while  adopting,  with  re- 
gard to  these  rocks,  a  view  the  very  opposite  of  that  main- 
tained by  Logan,  Foster  and  Whitney,  and  Dawson, — inasmuch 
as  he  denied  the  eruptive  origin  alike  of  many  of  the  crystiil- 
line  greenstones  of  one  series  and  of  the  bedded  granular  traps 
and  aniygdaloids  of  the  other, — was  led  to  agree  with  Logan, 
and  with  Dawson,  in  assigning  the  two  series  to  one  geological 
horizon,  and  in  regarding  their  mineralogical and  lithological  dif- 
ferences as  due  to  variations  in  the  degree  of  alteration.  This 
extreme  extension  of  the  doctrine  of  metamorphism,  which 
began  to  find  favor  with  other  geologists  about  the  same  time, 
was  the  natural  reaction  from  the  no  less  extreme  plutonism 
which  had  hitherto  prevailed,  and  marked  the  beginning  of  a 
revolution  in  geological  theory. 

§  158.  In  1857,  Prof.  J.  D.  Whitney  published  in  the  Ameri- 
can Journal  of  Science  ([2]  XXIII,  pp.  305-314)  a  review  and 
criticism  of  the  Laurentian  and  Huronian  systems  of  the 
Canada  geological  survey.     lie  therein  asserted  that  "there  is 


WHITNEY   ON    LAKE   SUPKItlOR. 


E.    Id 


no  evidence,  either  litliological  or  stratigrapliical,  for  separat- 
ing the  rocks  of  Lake  Huron  from  those  which  occur  farther 
east,  and  wliicli  are  classed  by  Mr.  Logan  as  Laurentian." 
Both  of  these,  Whitney  had  inchided  in  his  Azoic  series,  which 
lie  declared  to  consist,  alike  on  the  north  and  south  shores  of 
Lake  Superior,  ''of  talcose  and  hornblendic  slates,  and  gneisa- 
oidal  quartz-rock,  resting  on  a  granitic  and  syenitic   nucleus." 

§  159.  As  regards  the  cupriferous  series  of  the  north  shore 
of  lake  Superior, — the  upper  division  of  the  Volcanic  forma- 
tions of  Logan, — he  confirmed  the  opinion  of  the  latter,  that  it 
was  identical  with  that  of  the  south  shore.  He  had  himself 
examined  the  truppean  series  in  Ni{)igon  Bay  and  the  island  of 
St.  Iguace,  and  found  its  geological  structure  identical  with 
that  of  Isle  Koyalc  and  Keweenaw  Point.  (Geol.  Lake  Su- 
perior, II,  115.)  The  dark-colored  argillites,  cherts  and  sand- 
stones of  Thunder  Bay,  which  Logan  made  the  lower  division 
of  his  Volcanic  formations,  represent,  according  to  Whitney, 
only  "a  IocpI  variation  in  the  composition,"  analogous  to  "the 
dark-colored  and  highly  fissile  beds  of  the  Montreal,  Presque 
Isle  and  Iron  rivers  of  the  south  shore,  which  pass  gradually 
into  the  usual  red  sandstone  upwards  and  downwirds."  P'rom 
the  examination  of  this  series,  as  developed  in  the  south  shore, 
he  was  "unable  to  see  any  reason  for  separating  the  cupriferous 
range  from  the  sandstone  which  flanks  it  on  either  side." 

§  160.  Whitney  farther  declared  that  "  the  native-copper 
bearing  series  of  the  north  and  south  shores  of  Lake  Superior 
cannot  be  separated  from  the  Potsdam  sandstone  with  which  it 
is  associated  ;  neither  is  there  any  reason  whatever  for  placing 
it  in  the  same  line  with  the  rocks  of  the  north  shore  of  Lake 
Huron.  These  latter,  as  well  as  the  great  mass  of  crystalline 
rocks  to  the  north  and  east,  in  Canada,  are  identical  in  position 
and  lithological  character  with  the  series  described  by  Mr.  Fos- 
ter and  myself  under  the  name  of  the  Azoic  system,  and  which 
cover  so  large  an  extent  of  territory  in  Michigan,  Wisconsin 
and  Minnesota."  The  rocks  of  this  system,  according  to  Whit- 
ney, underlie  directly  the  trappean  copper-bearing  series,  alike 
on  the  north  and  south  shores  Ox  Lake  Superior. 

§  161.  The  reasons  of  these  opinions  were  given  at  length  in 
the  paper  quoted,  and  need  not  bo  discussed  here.     The  ver- 


m 


ii' 


80  K 


.SPECIAL  REPORT.      T.  STERRY   HUNT,  1875. 


V 


diet  of  later  investigationa  has  confirmed  the  previous  deter- 
minations of  tlie  Canadian  Burvcy,  botli  as  to  the  existence  ot 
two  distinct  and  unconformable  series  in  the  Azoic  system  of 
Whitney,  and  the  unconformable  infra  position  of  tlie  trapjican 
copper-bearing  series  to  the  so-called  Potsdam  sa    Istone  of  the 


region. 


In  his  other  principal  point,  however;  namely,  his  objection 

to  Logan's  early  attempt  to  establish  a  [larallelism  between  the 

upper  crystalline  schists  of  Lake  Huron  and  the  trappean  or 

Volcanic  copi»er-bearing  series  of  the  north  shore  of  liake  Su- 

l)erior,  Whitney  has  bet-n  fully  justitiod.     Jle  pointed  out  that 

,the  latter  had  t)een  declared  l)y  Logan  to  rest   unconfurmably, 

/in    Thunder    P>ay,  on  a  formation   of  crystalline  schists,  and 

'  these,  according  to  Whitney,  were  the  precise  equivalents  of 

those  of  Lake  Huron, — which  had  been  by  Logan  compared 

with  the  overlying  trappean  series.     There  was,  in  fact,  no  gf)od 

reason  for  this  view  of  Logan's, — in  which,  however,  he  had,  as 

we  have  soim,  been  followed  both  by  Kivot  and  by  Dawson, — 

and  in  the  latter  publications  of  the  geological  survey  of  Can- 

.  nda,  the  trappean  series  was,  in  accordance  with  the  view  of 

Whitney,  separated  from  the  lluronian,  but,  at  the  same  time, 

from  the  overlying  sandstones. 

§  1G2.  In  the  years  following  1849  no  further  attention  was 
given  by  the  Canadian  survey  to  these  rocks  on  Lake  Huron  or 
Lake  Superior,  until  in  1854-1858,  when  Mr.  Ahirray  made  his 
e2:tended  and  careful  geological  and  topographical  surveys  of 
the  northeastern  tributaries  of  Lake  Huron  and  the  region 
eastward.  These  explorations  furnished  many  details  of  the 
Laurentian  and  Huronian  series,  the  results  of  which  are  set 
forth  in  the  annual  rejiorts  for  the  years  mentioned.  From 
1858  to  18G8  no  aimual  reports  were  published  by  the  Canadian 
survey,  but  the  results  of  explorations  during  this  time  were 
embodied  in  the  volume  of  the  Geology  of  Canada,  published 
in  18(53  ;  in  the  Atlas  and  its  accompanying  text,  which  appeared 
in  1865;  and  in  the  larger  geological  map,  (§44)  published 
in  1866.  In  all  of  these  the  name  of  Huronian  was  restricted 
to  the  upper  crystalline  series  of  Lake  Huron  and  the  similar 
rocks  on  Lake  Superior,  where  their  distribution  had  been  care- 
fully studied  by  Mr.  Murray  in  the  years  1859  and  1860. 


MURRAY   ON  LAKE   SUPERIOR. 


E.    81 


his 
of 

<?ion 
the 
set 

roin 

lian 
'ere 

thed 
ired 
^hed 
3ted 
lilar 
lare- 


§  163.  In  the  Report  on  Lake  Superior,  in  184G,  an  area  of 
tlicso  crystalline  schists  had  heon  described  at  the  month  of  tho 
river  Dore,  and  their  presence  had  been  noticed  in  Thunder 
Bay  and  on  some  of  the  tributaries  of  the  lake.  Murray  found, 
in  addition  to  these,  a  large  extent  of  Iluronian  rocks  in  (ilou- 
lais  and  Batchowanung  Bays,  (which  were  mapped  in  the  At- 
las,) traced  them  at  intervals  along  the  shore  westward,  found 
a  still  larger  area  of  these  rocks  from  the  mouth  of  the  Pic  to 
the  Steel  river,  extending  far  into  the  interior,  and  studied 
their  distribution  in  the  vicinity  of  Thunder  Bay,  as  is  shown 
in  the  Atlas,  on  the  large  map,  and  in  the  Geology  of  ("anada 
(page  G3),  He  moreover  satisfied  himself,  by  comparative 
studies  on  the  south  shore  of  the  lake,  that  these  Iluronian 
rocks  were  identical  with  the  schistose  crystalline  rocks  of 
Whitney's  Azoic  series,  as  seen  at  the  iron-mines  in  the  vicinity 
of  Marquette.     (Ibid,  page  66.) 

§  164.  The  Volcanic  formations  of  the  north  shore  of  Lake 
Superior,  now  separated  from  the  Iluronian  (which  was  some- 
times distinguished  as  the  Lower  Copper-bearing  series)  were 
described  in  the  Geology  of  Canada  under  the  name  of  the 
Upper  Copper-bearing  series  of  Lake  Superior,  and  divided,  <a3 
before,  into  a  lower  and  an  upper  group  or  division,  (§  187)  no 
additional  details  as  to  its  geology  or  mineralogy  being  given. 
The  rocks  of  the  upper  division,  which  alone  hnd  been  traced 
to  the  eastward  of  Black  Bay,  were  described  as  having  an  east 
and  west  strike  from  the  west  end  of  the  lake  to  the  east  of 
Michipicoten  Island,  a  distance  of  300  miles.  This,  along  the 
eastern  border  of  the  lake,  was  exchanged  for  a  strike  nearly 
north  and  south,  the  amygdaloid  and  conglomerate  rocks  of 
Mamainse  and  Point  aux  Mines  having  a  marked  dip  to  the 
westward.  This  change  in  the  strike  is  apparent  for  nearly  100 
miles  along  the  eastern  shore,  and  in  the  vicinity  oi  the  nearly 
hoixzontal  sandstones  of  the  region,  from  the  undisturbed  at- 
titi.de  of  which  Logan  argued,  with  much  reason,  that  the 
sandstone  must  belong  to  a  newer  formation,  overlying  uncon- 
formably  the  Upper  Copper-bearing  series.  This  coincided  with 
the  early  opinion  of  llaughton.  (§  139.) 
6— E. 


^^- 


82  K 


SPECIAL   REPORT.      T.  BTERRY    HUNT,  1875. 


I;! 


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M 


§  165.  These  nearly  horizontal  sandstones  had  hitherto  been 
regarded  as  of  Potsdam  age,  but  the  similar  sandstones  to  the 
oast  of  Sault  Ste.  Marie  were  found  by  Hall,  and  by  Murray,  to 
be  conPormably  overlaid  by  a  series  of  limestones  liolding  the 
organic  remains  of  the  lower  divisions  of  the  Trenton,  with  in- 
dications of  the  Chazy  at  the  base ;  while  still  further  east  these 
limestones,  without  the  intervention  of  the  sandritoues,  rest  di- 
rectly on  the  older  crystalline  strata,  the  Calciferous  sandrock 
and  the  Potsdam  sandstone  of  the  New  York  series  being  ab- 
sent. It  was  therefore  suggested  by  Logan  that  the  sandstone 
might  itself  represent  the  Chazy,  in  which  case  the  unconform- 
ably  underlying  copper-bearing  series,  with  its  amygdaloids 
and  bedtiod  traps,  "  might  reasonably  be  considered  to  belong 
to  the  Calciferous  and  Potsdam  formations."  (Ibid,  pages  80- 
87). 

Resting  upon  the  sandstone  on  the  south  side  of  Kewcnaw 
Point,  Fortter  and  Whitney  found  a  magnesian  limestone  which 
also,  according  to  Hall,  contains  the  organic  remains  of  the 
base  of  the  Trenton.  The  sandstones  of  tlie  region  have  more- 
over yielded  a  species  of  Lingula  at  Tequameneu  Bay,  and  at 
MarquettH  a  cast  of  -  Pleurotomaria,  the  species  of  neither  of 
which  could  not  be  satisfactorily  identified.  (Hall,  16th  Report 
to  the  Regents  of  the  University  of  New  York,  pages  214-215  ; 
Geology  of  Canada,  page  86,  and  Report  of  the  Geological  Sur- 
vey of  Canada,  1866-69,  page  475). 

Of  the  farther  development  of  Logan's  new  suggestion  as 
to  the  age  of  the  trappean  copper- bearing  rocks,  which  led 
him,  in  a  later  chapter  of  the  Geology,  (18(53,)  and  in  the 
Atlas,  to  refer  them  to  what  he  called  the  Quebec  group,  we 
shall  treat,  after  having  described  the  progress  of  geological 
investigations  in  the  province  of  Quebec.  We  sliall  then  also 
consider  the  opinion  advanced  by  certain  investigators,  at  an 
early  period  in  the  study  of  the  geology  of  Lake  Superior, 
that  the  copper-bearing  rocks  are  of  Mcsozolc  age. 

§  166.  We  have  ab-eady  seen  that  the  sedimentary  rocks 
from  the  eastern  shore  of  Lake  Chani})lain  had  been  declared 
by  Emmons,  in  1842,  to  extend  north-eastward  as  far  as  (Que- 
bec, whei-e  were  displayed  the  upptr  members  of  the  Cham- 
plain  division,  at  times  confounded  by  him  with  the  rocks  of 


THE  QREEX  MOUNTAIN  RANGE  IN  CANADA. 


83.  E. 


the  Taconic  system  (§  112-113).  Along  the  south-eastern  bor- 
der of  these  sedimentary  strata  rises  a  chain  of  hills  of  crys- 
talline rock,  which  are  the  prolongation  of  the  Green  Moun- 
tains of  Vermont,  and  are  sometimes  known  in  Canada  as  the 
Notre  Dame  range.  This  belt  has  a  breadth  of  about  thirty 
miles  on  tiie  frontier  of  Vermont,  which,  on  the  St.  Francis, 
is  reduced  to  about  twelve  miles,  but  in  its  extension  tu  the 
north-east,  where  it  is  intersected  by  the  Chaudi^re,  broad- 
ens again  to  ita  former  width.  Tlie  range  attains  in  the  hills 
of  Sutton,  Orford,  Ilam  and  Cranbourne,  heights  of  more  than 
3,000  feet  above  tne  sea,  but  a  little  to  the  east  of  the  Etche- 
min  river,  and  south  of  the  island  of  Orleans,  disappears  be- 
neath the  sedimentary  rocks,  after  a  course  of  about  150  miles 
from  the  frontier  of  Vermont. 

§  167.  These  crystalline  rocks  reappear  again  to  the  north- 
east, after  an  interval  of  more  than  250  miles,  within  twelve 
miles  of  the  south  shore  of  the  St.  Lawrence,  between  the 
rivers  Matanne  and  Ste  Anne  in  Gasp^,  where  they  form  a 
narrow  belt  similar  to  the  Notre  Dame  range,  known  as  the 
Shickshock  Mountains,  wldch  rise  to  the  height  of  3,000  feet 
and  extend  for  a  distance  of  about  sixty  miles  in  a  direction 
east-northeast.  Beyond  the  Shickshock  Mountains,  to  Cape 
Rosier,  the  northeast  point  of  the  peninsula  of  Gaspe,  a  dis- 
tance of  nearly  ninety  miles,  the  country  in  their  range  is  oc 
cupied,  like  the  interval  between  the  Etchemin  and  Matanne 
rivers,  by  uncrystalline  sedimentary  rocks. 

This  account  of  the  distribution  of  the  rocks  of  the  Green 
Mountain  belt  to  the  northeast  is  rendered  necessary  from  the 
fact  that  the  geological  maps  of  Canada,  hitherto  published, 
fail  to  make  any  distinction  between  the  crystalline  rocks  and 
the  sedimentary  strata,  which  are  found  in  the  strike  of  these 
to  the  northeast,  and  moreover  bound  them  on  the  north  and 
west.  These  two  unlike  classes  of  rocks  were  by  Logan  sup- 
posed to  be  one  and  the  same  series  in  ditterent  mineral  condi- 
tions, and  in  accordance  with  this  view  the  maps  are  so  colored 
that  it  is  made  to  appear  as  if  the  crystalline  belt  of  the  Green 
Mountains  were  continuous  to  the  northeastern  extremity  of 
the  continent. 


84  E. 


SPECIAL    REPORT.      T.  STERRY  HUNT,  1875. 


§  1G8.  To  the  oast  and  south,  these  crystalline  rocks  are  over- 
laid (generally  with  an  intervening  series  of  HrL;!;illites)  by  lbs 
siliferous  limestones  belonu:inj;  to  the  Silurian,  whicli  are  traced 
from  the  valley  of  Jjake  Meniphramiigog  northeastwards  to  the 
extremity  of  Gaspe,  and  in  their  northeastern  extension  are 
overlaid  by  a  great  mass  of  Devonian  sandstones  and  shales, 
generally  called  the  Gaspe  sandstones,  which  pass  beneath  the 
coal-basin  of  New  Brunswick.  These  newer  rocks,  wliere  tlie 
crystalline  schists  are  absent,  rest  unconforniably  upon  the  older 
sedimentary  strata.  The  pyritiferous  clay-slate  formation,  pre- 
viously declared  to  exist  on  the  southeast  side  of  the  St.  Law- 
rence, (§  1-7)  included  the  unlike  artiillitos  of  the  two  sides  of 
the  crystalline  belt,  as  well  as  some  of  the  more  schistose  por- 
tions of  tlie  latter. 

§  1(39.  The  older  and  greatly  disturljcd  sedimentary  strr-ta, 
which,  as  already  indicated,  bound  to  the  west  and  the  north 
the  crystalline  rocks  of  this  region,  are  a  prolongation  of  the 
Upper  Taconic  rocks  from  western  Vermont,  and  are  themselves 
limited  to  the  northwest  by  strata  belonging  to  ditfcrent  mem- 
bers of  the  Champlain  division.  These  are  traced  from  Lake 
Champlain  along  the  Richelieu  river,  and  thence  to  the  north- 
east, occupying  both  sides  of  the  St.  Lawrence,  to  the  vicinity 
of  Quel)cc,  and,  unlike  the  sedimentary  belt  to  the  east  and 
south  of  them,  are  comparatively  undisturbed, and  nearly  hori- 
zontal. A  transvei-se  section  from  the  Lanrentides  across  this 
part  of  the  St.  Lawrence  valley,  traversing  the  Notre  Dame 
range  to  the  valley  occupied  by  Lake  Memphramagog  and  the 
ujii)er  part  of  the  river  St.  Francis,  gives  essentially  the  same 
geological  succession  as  one  from  the  Adirondacks  across  Lake 
Champlain  and  the  Green  Mountains  to  the  Connecticut  valley, 
except  that  the  characteristic  quartz-rock  end  granular  lime- 
stone of  the  Lower  Taconic,  are  scarcely,  if  at  all,  represented 
to  the  north  of  the  Vermont  frontier. 

§  170.  It  was  in  1847  that  Sir  W.  E.  Logan,  accompanied  by 
the  present  writer,  began  the  study  of  the  rocks  of  this  region, 
from  Lake  Champlain  to  the  vicinity  of  Quebec,  a  work  which 
was  continued  during  a  part  of  the  summer  of  1848.  The  re- 
sults of  these  two  years  of  labor  were  resumed  in  the  Report  of 
1847,  the  publication  of  which  was  retarded  until  1849,  in  or- 


QEOLOaY   OP    EASTERN   CANADA. 


E.    85 


del"  to  present  more  complete  results,  as  is  explained  in  the  i)re- 
face  to  this  Report,  and  uLho  in  the  Report  of  1848,(i)age  Gj  pub- 
lished in  1860.  A  statenient  of  the  conclusions  reached  at  that 
time  with  regard  to  the  geology  of  Canada,  including  the  re- 
gion in  question,  will  be  found  in  a  paper  read  by  the  present 
writer  before  the  Anjcrican  Association  for  the  Advancement 
of  Science  at  Cambridge  in  1849,  and  published  in  the  Ameri- 
c;in  Journal  of  .Science  for  January,  1850.  ([2]  vol.  IX,  j'p.  12- 
19.) 

§  171.  The  belt  of  sedimentary  strata,  already  descriltcd  as 
bounding,  on  the  west  and  north,  the  highly  inclined  crystalline 
rocks  of  the  Notre  Dame  range,  was  found  to  consist  chieHy  of 
argillites  with  sandstones  and  conglomerates,  including  some 
masses  of  limestone,  the  whole  in  a  greatly  disturbed  condi- 
tion, and  was  correctly  recognized  by  the  Canadian  survey  as 
the  prolongation  of  the  Argillite  and  Graywacke  series  ot  the 
east  side  of  the  Hudson  River. 

in  the  Report  for  1847,  (embodying  the  results  of  1848,)  the 
views  of  Matter,  already  set  forth  (§§  08-73),  were  a(lo[)ted, 
together  with  those  of  Emmons,  as  alreaily  defined  (§§  Go,  112, 
113),  and  these  rocks  in  Canada  were  referred  to  tlie  upper 
portion  of  the  Chani{)lain  division,  under  the  name  of  the 
Hudson  River  gronj),  and  to  the  Shawangunk  or  Oneida  of  the 
succeeding  Ontario  division.  The  limestones  of  riiillijisburg, 
on  Lake  Champlain,  the  oidy  fossiliferous  strata  then  known 
iu  this  belt,  were  regarded  as  of  Trenton  age. 

§  172.  The  crystalline  rocks  of  the  Notre  Dame  range  were 
at  the  same  time  described  as  including  clay-slates,  micaceous, 
talcose,  and  chloritic  schists,  often  with  much  epidote,  quartz- 
ites,  ferriferous  dolomites  and  magnesitos,  steatites  and  ser- 
pentines, with  massive  diallagic,  hornbhindic,  jiyroxenic  and 
feldspathic  rocks;  the  whole  associated  with  beds  of  magnetite, 
red  hematite,  titanic  and  chromic  iron,  and  with  sulphuretted 
ores  of  copper  and  native  gold.  The  serpentines  were  shown 
to  be  banded  interstratified  masses,  occupying,  like  the  steatites 
and  dolomites,  a  determinate  place  in  the  stratification.  Two 
sections  were  then  made  across  the  belt,  tlie  one,  a  few  miles 
north  of  the  Vermont  frontier,  and  the  other,  on  the  St.  Fran- 
cis river,  of  both  of  which  detailed  accounts  were  given.     The 


ii 


M;: 


86  E. 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


strata  were  shown  to  be  lii^hlj'  inclined,  and  aft'ected  by  numer- 
ous sharp  undulations,  the  directions  of  which  conformed  with 
that  of  the  mountain  chain. 

§  173.  The  rocks  of  the  Notre  Dame  range,  it  was  said, 
"  though  stratified,  are  highly  crystalline,"  but,  it  was  main- 
tained, "  are  to  be  considered  not  Primary,  but  Metamorphic." 
(Report  of  1847,  p.  30).  They  were  regarded,  in  acct>rdance 
with  the  views  of  Mather,  (§  80-81,)  whose  Report  on  the  South- 
ern district  of  New  York  was  at  tliat  time  carefully  studied  by 
tlie  Canadian  Survey,  as  having  resulted  from  the  alteration 
ot'  the  strata  of  the  Hudson  River  group,  which  were  supposed, 
at  certain  points  along  the  line  of  contact  between  the  two,  to 
exhibit  evidences  of  a  gradual  passage  from  the  uncrystalline 
sediments  to  the  crystalliae  schists,  in  summing  up  the  facts 
detailed  in  elucidation  of  the  structure  of  the  Notre  Dame 
range,  designated  as  "  the  Green  Mountains  in  their  Canadian 
prolongation,"  the  conclusion  was  reached  that  "  the  whole  of 
the  Green  Mountain  rocks,  including  those  containing  the  au- 
riferous quartz  veins,  belong  to  the  Hudson  River  group,  with 
the  possible  addition  of  part  of  the  Shawangunk  conglomer 
ates."     (Ibid,  page  57.) 

§  174.  The  section  along  the  St.  Francis  was  continued  from 
Sherl.rooke  southeastwards  across  the  limestones  of  the  valley, 
and  thence  to  Canaan,  in  the  northeastern  corner  of  Vermont. 
The  rocks  were  described  as  soft  argillaceous,  micaceous  and 
calcareous  schists,  highly  pyrititerous,  succeeded  by  harder  mi- 
caceous and  quartzose  strata,  often  with  garnets  and  chiasto- 
lite,  associated  with  beds  containing  black  hornblende,  and 
with  granites.  The  latter  were  regarded  as  intrusive,  which 
is  true  uf  a  portion  of  the  granitic  rocks  of  the  region.  These 
strata  were  found  to  be  highly  inclined,  with  a  prevailing  in- 
clination to  the  north-west,  the  latter  ]iart  of  the  section  form- 
ing a  bold  range  of  hills,  in  which  the  Connecticut  and  Chau- 
diere  rivers  take  their  rise.  No  detailed  examination  was 
made  of  that  part  of  the  line  of  section  from  the  limestones  of 
the  valley  of  Lake  Massawippi  to  Canaan  ;  the  description  of 
it  given  in  the  Report  for  1847  having  been  taken  from  the 
notes  made  by  Logan  during  a  journey  across  the  region  aa 
early  as  1842.     He  however  ventured,  in  accordance  with  the 


will 


GEOLOGY  OF  EASTERN  CANADA. 


E.  87 


views  which  had  been  advanced  by  Mather  and  the  Messre.  Rog- 
ers,  (§  123)  to  assign  these  rocks  to  a  higher  geok^gical  horizon 
than  the  Green  Mountains,  and  while  the  whole  of  the  inter- 
vening calcareous  strata  were  supposed  to  be  Silurian,  to  put 
forth  the  siitrgestion  that  the  mica-slates,  with  hornblendic, 
gneissic  and  granitic  rocks,  were  perhaps  of  Devonian  age,  being 
"a  part  of  the  Gasp6  sandstones  in  an  altered  state."  (Report 
of  1847,  pages  55-58). 

§  175.  During  the  year  1849,  the  investigation  of  the  Notre 
Dame  range,  and  of  the  disturbed  sedimentary  belt  along  its 
western  and  northern  boundary  was  continued,  the  latter  being 
examined  at  various  points  from  the  northern  extremity  of 
Lake  Champlain  as  far  as  tlie  vicinity  of  Quebec,  and  thence 
along  the  nortliern  shore  of  the  8t.  Lawrence  for  about  130 
miles,  to  the  Temiscouata  portage,  a  road  leading  to  the  lake  of 
that  name.  The  results  of  these  investiirations  are  set  forth  in 
the  R«port  for  1849,  publislied  in  1850  (pages  31-64).  Jjogan 
was  aided  in  this  field-work  by  Murray,  and  by  the  present 
writer.     (Ibid,  pages  6,  73.) 

In  describing  the  general  distribution  of  the  rocks  along  the 
south  shore  of  the  St.  Lawrence,  we  have  already  made  use  of 
this  exploration,  and  also  of  that  of  1844.  In  this  latter  re- 
port Logan  had  given  (pages  17-30)  the  results  of  his  exami- 
nation of  this  coast  from  Capo  Chatte,  a  point  a  little  farther 
east,  to  Cape  Rosier  at  the  extremity  of  the  peninsula  of 
Gaspe,  and  had  also  described  the  newer  limestone  and  sand- 
stone-formations lying  to  the  southward,  (§  168)  which  were 
then  designated  the  Gaspe  limestones  and  the  Gaspe  sandstones 
(pages  31-66). 

§  176.  The  opinion  was  expressed  in  1844,  that  these  coastal 
rocks,  or  at  least  a  portion  of  them,  are  ''  the  equivalent  of  a 
part  of  the  Hudson  River  group  of  the  Xew  York  geologists" 
(page  21).  It  was  aiterwards  elearly  apparent  that  they  were 
similar  to  those  found  along  the  ooast  between  the  Temiscouata 
road  and  Quebec,  and  to  the  belt  now  traced  from  Quebec  to  Lake 
Chamjilain.     These,  as  we  have  seen  in  the  Report  for  1847, 


were  also  referred  to  the  Hudson  River  ir 


roup, 


rcirarded  as  bo- 


longing  to  the   upper  part  of  the  C!hamplain  division  of  tho 
^ow  York  series,  and  m  the  same  Report  (page  58)  reference 


!!;■ 


!  |i. 


88  E. 


SPECIAL    REPORT.      T.  STERRY    UlTNT,  1875. 


was  made  to  "  the  continuous  run  of  the  reco2:nizcd  rocks  of 
the  Hudson  River  group  from  Lake  Chanipluin,  along  the  south 
side  of  the  St.  Lawrence,  to  Cape  Rosier."  In  the  Rei)ort  for 
1849  (page  18)  it  was  again  mentioned  that  "  a  formation  con- 
temporaneous with  the  Hudson  River  group,  superior  to  the 
Trenton  limestone,  extends  along  the  south  side  of  the  St.  Law- 
rence from  Point  Levis  (opposite  Quebec)  to  (Jape  Rosier."  The 
continuity  of  this  belt  of  sedimentary  rocks,  along  the  east 
side  of  Lake  Chaniplaiu,  with  the  similar  rocks  to  the  east  of 
the  Hudson — the  Argillite  and  Graywacke  series  of  Eaton — bad 
already  been  established  by  Emmons  and  by  Ma 'her,  as  shown 
in  the  preceding  chapter. 

§  177.  The  observations  of  Mather  and  Emmons  as  to  the 
singularly  disturbed  and  often  inverted  attitude  of  these  strata 
in  the  regions  just  mentioned  were  abundauiiy  confirmed  by  the 
oflicers  of  the  geological  survey  of  Canada.  The  belt  be- 
tween Lake  Chaniplaiu  and  the  Tennscouata  road  is  described 
as  presenting  "a  multitude  of  anticlinal  axes,  over  which,  in 
succession,  the  strata  bend  in  sharp  plications,  often  leaning 
over  to  the  northwest,  giving  the  semblance  of  a  nearly  con- 
stant dip  to  the  south-east,  at  high  angles.  These  folds  are  so 
numerous,  and  frequently  repeat  the  measures  several  times  in 
so  short  a  distance,  as  to  destroy  confidence  in  every  endeavor 
to  estimate  the  thickness  of  the  different  divisions  of  the  de- 
posit ;  and  the  want  of  knowledge  of  the  true  tliickness,  on 
the  other  hand,  renders  it  uncertain,  in  any  particular  case  un- 
der examination,  whether  all  the  folds  afiecting  a  set  of  strata 
have  been  correctly  ascertained.  The  main  undulations  can  of- 
ten be  followed  for  considerable  distances  by  means  of  the  geo- 
graphical distribution  of  contorted  masses  of  the  sub  divisions, 
but  unless  a  connection  or  relation  with  regard  to  each  other 
is  followed  out  among  these  undulations,  it  is  somewhat  difli- 
cult  to  determine  whether  a  form  that  may  be  subject  to  con- 
sideration is  synclinal  or  anticlinal."  (Report  for  1849,  pp. 
31-8±) 

§  178.  An  illustration  of  this  inversion  of  strata  is  seen  in 
the  Report  for  1847  (page  24),  where,  in  Granby,  not  far  to  the 
north  of  Lake  Champlain,  the  red  and  green  sandstones  of  the 
series  in  question  are  said  to  be  folded  in  a  great  overturned 


INVERBIONS   OF    STRATA. 


E.  89 


Byuclinal,  in  which  the  strata,  on  both  sides  of  the  basin,  dip 
to  the  Boutheast  at  angles  varying  Iroai  45°  to  80°. 

Still  more  remarkable  examples  of  this  are  shown  in  the 
Kcport  for  1844,  in  the  account  of  the  same  belt  ou  the 
south  shoio  below  Quebec,  where  it  is  said  that  the  rocks  "as 
they  come  out  on  the  .St.  Lawrence  exhibit  a  very  contorted  con- 
dition. The  tlexures  are  numerous,  and  some  of  them  are  so 
violent  that  serious  inversions  of  the  strata  sometimes  present 
themselves,  and  it  is  frequently  very  difficult  to  determine 
whether  the  mass  under  inspection  be  a  new  member  of  the  de- 
posit, or  a  repetition  of  one  previously  noted."  (Keport  for 
1844,  page  18.) 

§  179.  Numerous  examples  of  this  are  given,  one  of  which 
is  on  the  east  side  of  the  lliviere  I'ierre,  where  the  summit  of 
the  hill  sliows  an  overturn  d\\),  and  the  strata  in  the  whole  sec- 
tion appear  to  be  arranged  in  the  ibrm  of  a  very  flat  S'  Farther 
down  on  the  coast  *  *  *  there  are  evidences  of  an  over- 
turn dip,  *  *  *  and  a  little  under  two  leagues  above  Capo 
Magdalen,  and  about  the  same  distance  from  Gros  Male,  the 
apex  of  the  flexure  connected  with  it  comes  out  upon  the 
shore.  The  direction  of  the  anticlinal  axis  appears  to  be  N. 
65°  W.,  magnetic,  and  proceeding  from  it  upwards  along  tlie 
beach  the  strata,  presenting  at  first  a  north  dip  of  20°  to  40°, 
gradually  bcoome  vertical ;  further  on  they  overhang  ;  still 
further  the  overturn  increases,  and  the  beds,  becoming  flat,  with 
the  bottom  upwards,  in  this  inverted  position,  roll  farther  over, 
and  for  a  short  distance  slope  slightly  northward.  From  tliis, 
however,  they  recover,  after  no  great  interval,  but  tiually  in 
Gros  Mille  bluff,  they  exhibit  a  short  twist,  occupying  about 
twenty  feet  in  the  upper  part  of  the  cliff,  in  which,  after  re- 
turning to  an  uninverted  north  dip,  they  are  again  canted  over 
to  a  nearly  horizontal  position,  with  tiie  bottom  upwards. 
Tlio  inverted  beds  examined  extend  upwards  of  five  miles  along 
the  shore,  and  though  the  twists  in  the  north  side  of  the  anti- 
clinal, which  roll  them  over  to  an  upside-down  north  dip,  are 
short,  and  therefore  do  not  produce  so  imjiortant  a  result  as  the 
simple  overturn  south  dip,  they  serve  to  illustrate  the  comjilica- 
tion  of  the  strata,  and  the  difficulty  of  disentangling  them  in 


pi' 
hi 


I.,: 


I 


90  E. 


SPECIAL    REPORT.      T.  8TERRY    HUNT,  1875. 


I|:l 


endeavoring  to  follow  out  the  order  of  superposition."  (Ibid, 
pp.  23-24.) 

§  180.  The  strata  in  this  disturbed  region,  below  Cape  Chatte, 
were  described  as  consisting  of  great  masses  of  sandstone, 
the  vertical  beds  of  which,  by  the  action  of  the  sea-waves,  are 
wrought  into  upright  columns,  known  to  the  navigators  as  Pil- 
lars, for  which  reas^on  these  rocks  were  called,  in  the  Report, 
the  Pillar  sandstones.  These  sandstones,  which  are  greenish 
in  color  and  often  conglomerates,  holding  pebbles  of  quartz  and 
others  of  black  shale,  were  found  to  be  associated  with  bands 
of  red,  and  more  rarely  with  black  argillaceous  slates.  A  nother 
portion  of  the  series  consisted  of  gray  calcareous  sandstones 
and  gray  limestones,  sometimes  oolitic  in  structure,  together 
with  conglomerates  composed  chieily  of  limestone  pebbles,  in- 
terstratitied  with  green  and  black  argillites.  Other  portions 
presented  thin-bedded  limestones  with  gray  sandstones  and 
black  shales  holding  graptolites. 

§  181.  In  the  Heport  for  1819  an  attempt  was  made  to  estab- 
lish the  succession  of  these  rocks  "in  ascending  sequence  from 
the  Trenton  limestone  and  Utica  slate.''  They  were  then  di- 
vided into  live  groups,  as  follows: 

1.  Dark  gray  clay-slates,  with  gray  thin-bedded  sandstones, 
often  calcareous,  and  with  gray  limestones,  both  weathering  yel- 
lowish-brown. This  division  holds  shells  and  graptolites,  and 
appears  to  be  terminated  by  bituminous  shales  and  black  lime- 
stones. 

2.  Gray,  green  and  red  shales,  with  thin  calcareous  layers 
and  bands  of  calcareous  conglomerate. 

3.  llard  gray  sandstones,  rarely  greenish,  frequently  becom- 
ing conglomerate  from  pebbles  "of  gray  limestone  containing 
organic  remains  of  the  Trenton  formation,''  besides  thin-bed- 
ded gray  limestones. 

4.  Red  and  green  and  chocolate-colored  shales,  often  inter- 
stratifiod  with  thin  bands  of  light  gray  sandstone,  which  is 
sometimes  calcareous. 

5.  (Joarse -grained,  green,  massive  sandstones,  holding  scales 
of  mica  and  grajthite.  "They  appear  to  derive  their  prevailing 
color  from  chlorite,  but  rod  layers,  as  coai-se  as  the  green,  and 
holding  nearly  as  much  chlorite,  are  in  some  parts  interstrati- 


CHLORITIC  SANDSTONES  OF  QRANDY. 


E.  91 


Hi- 


es 


If 


lied."  These  rocks  are  often  coarsely  conglomerate,  with  quartz 
pebbles,  "which  sometimes  ap[)ear  to  become  mingled  witli  peb- 
bles and  even  boulders  of  gray  limestone,  holding  fossils  proba- 
bly of  the  Trenton  formation."  lied  and  green  slates  are  in- 
terstratified  with  this  division. 

§  182.  This  succession,  the  description  of  which  is  abridged 
from  tliat  given  in  the  Report  of  1849,  was  determined  almost 
wholly  from  the  section  seen  near  Quebec,  on  the  island  of  Or- 
leans and  at  Point  Levis,  although  details  of  some  of  the  di- 
visions were  iiathcred  from  other  localities.  The  rey-ion  farther 
eastward  was,  as  already  shown,  too  much  disturbed  to  give 
any  satisfactory  evidence  as  to  the  sequence,  while  to  the  south- 
west the  strata  are  concealed,  for  long  intervals,  by  the  great 
mass  of  superficial  deposits,  and  but  few  outcrops,  and  these  of 
small  portions  of  the  series,  are  met  with.  Thus,  the  fossili- 
ferous  limestones  are  known  to  the  southwest  of  Toint  Levis 
within  the  limits  of  the  province,  only  at  and  near  Phillipsburg 
on  Lake  Champlain.  The  green  sandstones  of  the  scries  are 
not  met  with  in  this  vicinity,  but  are  seen  a  little  to  the  north- 
ward, in  Milton,  Roxton  and  Granby,  and  at  various  points 
from  the  8t.  Francis  river  to  tlie  vicinity  of  Quebec,  beyond 
which  they  are  larj.'ely  displayed  in  the  region  to  the  northeast* 

§  183.  The  presence  of  chlorite  in  these  sandstones  was  no- 
ticed at  several  localities  below  Quebec  in  the  interval  between 
the  crystalline  rocks  of  the  Notre  Dame  and  the  Shickshock 
Mountains,  (Report  ot  1849,  page  47)  and  also  in  Granby  (Re- 
port of  1847,  [lage  25).  Here  the  green  sandstones,  with  some 
red  beds,  are  occasionally  calcareous,  and  often  conglomerate, 
holding  pebbles  both  of  quartz  and  of  feldspar,  together  with 
scales  of  mica  and  of  graphite,  and  constituting  an  arkose. 
The  grapiiite,  and  the  chlorite  to  which  they  owe  their  color,  are 
more  abundant  in  the  finer  than  in  the  coarser  l)eds.  Inter- 
stratified  with  these  sandstones,  and  with  red  and  green  slates, 
some  of  which  also  abound  in  scales  of  mica  and  of  chlorite, 
are  two  calcareous  layers,  one  and  two  feet  in  thickness,  earthy 
in  texture,  and  weather  ,ng  brownish  from  the  presence  of  man- 
ganese, but  witiiin  of  a  green  color,  evidently  due  to  a  large 
admixture  of  chlorite,  (as  was  shown  by  a  jiartial  analysis  at  the 
time,)  and  containing  a  small  proportion  of  oxyd  of  chromium. 


I 


lu 


r 

I 

i 

t- 

1 

'■    hIi 

wnr 


92  E 


SPECIAL   REPORT.      T.  3TERRY    HUNT,   1875. 


t:     ^ 


A  careful  study  of  this  locality  waia  BubHequently  made  by  the 
writer,  and  the  results  of  a  chemical  unalytiis  are  given  in  the 
Report  for  1853-5G  (page  474).  The  green  earthy  mass  held 
inibedded  scales  of  chlorite,  and  yielded  to  dilute  acids  about 
30.0  per  cent  of  carbonate  ol  lime,  besides  small  portions  of 
magnesia,  manganese,  iron  and  alumina.  The  residue  con- 
tained no  lime,  but  gave  of  silica,  53.20  ;  alumina,  7.90  ;  pro- 
toxyd  ot  iron,  15.75;  magnesia,  8.79  ;  titanic  acid,  0.30  ;  oxyds 
of  manganese,  chromium,  nickel,  ami  loss,  2.00  ;  alkalies,  0.00  ; 
volatile,  4.80=100.00.  The  oxyd  of  chromium  was  found 
equal  to  0.30,  and  that  of  nickel  to  0.15  per  cent. 

^  184.  The  presence  of  these  chemical  elements,  and  of  the  dis- 
seminated chlorite,  wiiicli  evidently  forms  a  cojisiderable  pro- 
portion of  the  matter  analysed,  were,  at  the  time,  considered 
as  evidences  of  a  commencement  of  metamorphism  in  the  sedi- 
mentary strata,  and  as  marking  the  passage  of  these  into  the 
crystalline  rocks  of  the  Notre  Dame  range,  which,  in  accordance 
with  the  view  then  held  by  most  American  geologists  (as  set  forth 
in  the  preceding  chapter),  were  supposed  to  be  no  other  than 
these  same  strata  in  a  highly  altered  condition  and,  in  the  imme- 
diate vicinity  of  Grauby,  abound  in  chloritic  schists,  and  in  titan- 
iferous  iron  ores,  with  manganese,  chrome  and  nickel.  The 
more  sim[)le  and  obvious  view  that  these  matters,  like  the 
quartz,  feldspar,  graphite  and  mica  of  the  arkose,  had  come 
from  the  disintegration  of  the  adjacent  crystalline  formation  was 
then  rejected  by  the  writer,  as  being  incompatible  with  the 
notion  of  the  contemporaneous  origin  of  the  two  series  of  crys- 
talline and  uncrystalline  rocks,  which  was  at  that  time  unques- 
tioned, except  by  Emmons.  This  geologist,  as  we  have  seen 
(§  05,  107),  had  already  noticed  the  existence  of  chlorite  in 
these  sandstones  in  Vermont  and  in  New  York,  but  main- 
tained that  it  was  derived  from  the  ''chloritic  slate  alonsi  the 
eastern  border,"  and  also  suggested  the  presence  in  these  sand- 
stones of  the  "debris  of  hornblende." 

§  185.  These  sandstones,  where  they  appear  on  the  St.  Fran- 
cis river,  arc  traversed  by  dykes  of  greenstone,  and  about  two 
miles  below,  in  Wendover,  is  a  great  development  of  green- 
stone, sometimes  porj)hyritic,  and  at  other  times  amygdaloidal, 
with  agates  and  calcite.     These  masses  are  apparently  conform- 


GREENSTONES    AND   COPPERBEARINQ   STRATA. 


E.  93 


an- 

le 


•iin- 
wo 
■en- 
liil, 

I'lU- 


uble  to  the  stratitication,  and  are  associated  witli  graptolitic 
shales,  into  which  the  aniVL''daloid  seems  to  •graduate.  tSuine  of 
the  beds  are  apparently  a  breccia,  made  up  of  Iragnients  of  the 
porphyritic  greenstone,  cemented  by  calcite  (Geology  of  Can- 
ada, 1803,  pages  243,  710).  The  greenstones  are  traversed  by 
brccciated  veins  carrying  sulpliuretted  ores  of  c()i)per.  Simi- 
lar greenstones  and  amygdaloidsarei'ound  fartlier  northeast  in 
the  same  strike,  at  St.  Flavien,  interstratiiied  with  red  slates 
and  calcareous  conglomerates.  Here  also,  sulphuretted  copper 
ores  are  found  both  in  the  strata  and  in  transverse  veins,  in  ad- 
dition to  which  native  copper  occurs  witii  calcareous  spar  in 
druses  in  the  conglomerate.  "  The  whole  band  has  a  striking 
resemblance  to  some  of  the  rocks  of  the  Upper  Copper-bearing 
series  of  Lake  Superior."     (Ibid,  pages  242,  720.) 

§  18G.  In  the  extension  of  this  belt  to  the  southwest  of  the 
St.  Francis  large  beds  of  magnesiun  limestone  are  found,  asso- 
ciated with  dark  gray  slates,  and  abounding  in  a  fueoid  resem- 
bling Buthotrephis  Jiexuosa  of  Emmons.  These  are  accompanied 
with  great  interbedded  masses  of  greenstone,  like  those  of 
Wendover  and  St.  Fiavien,  while  the  limestones  contain,  in  nu- 
merous localities,  sulphuretted  copper  ores,  as  in  Wickham, 
Durham,  Upton  and  at  Actouvale,  where  a  mine  was  formerly 
wrought  from  which  rich  ores,  yielding  over  1,0U0  tons  of  cop- 
per, were  extracted.  These  ores  were  chietiy  found  in  a  lime- 
stone-conglomerate, occasionally  presenting  the  aspect  of  a  brec- 
cia, the  fissures  of  which  were  filled  with  variegated  ore,  calcite 
and  quartz ;  and  at  other  times  forming  a  compact  mass,  in  which 
rounded  and  angular  fragments  of  limestone,  and  others  of  chert, 
were  enclosed  in  a  paste  of  vitreous  and  variegated  sulphurets 
of  copper,  which  are  seen  in  polished  sections  to  present  a 
banded  or  stratified  arrangement.  The  conditions  at  Upton, 
where  copper-py rites  occurs, are  very  similar.  (Geology  of  Cana- 
ada,  18G3,  pages  241-244;  712-720.) 

§  187.  The  greenstones  of  Actonvale  and  Upton  were  exam- 
ined chemically  by  the  present  writer,  and  found  to  consist  of 
a  basic  feldspar,  sometimes  clcavable,  with  hornblende  or  pyr- 
oxene, and  an  amorphous  green  hydrated  silicate  related  to 
chlorite.     They  were  shown  to  resemble  closely  in  composition 


f\ 


94  E. 


SPECIAL  REPORT.      T.  STEKRY    HUNT,  1875. 


II    ::i! 


the  greenstones  described  by  Wliitncy  from  tlic  Upper  Cop[ter- 
beariiii^  rocks  of  LuKe  Supori(jr.     (Ibid,  {)uge  004.) 

§  188.  Tills  remurkablo  dovelopineiit  of  cop{>or  ores  along  a 
portion  of  the  belt  does  not  seem  to  be  dependent  upon  the 
presence  of  the  greenstones,  since  the  ores  appear  in  the  Tune- 
stones  in  Wickhamand  Durham,  near  Actonvale,  where  the 
greenstones  are  unknown.  This,  moreover,  is  the  case  at  St. 
Henri  and  Point  Ijcvis,  near  Quebec,  in  both  of  which  places 
the  red  slates  of  the  series  contain  jilatcs  and  masses  of  native 
copper,  sometimes  of  several  pv^unds  weight,  it  is  j)robably 
however  to  the  presence  of  these  hard  greenstone  rocks  that 
are  due  many  outcrops  of  the  soiter  copper-bearing  limestones, 
which  elsewhere  are  worn  down  and  concealed  beneath  the  su- 
perficial deposits. 

§  189.  We  have  now  to  inquire  into  the  reasons  which  led 
tlie  geological  survey  of  Canada  to  assign  the  sedimentary 
rocks  on  the  south  side  of  the  St.  Lawrence  to  the  upper  part 
of  the  Chami)lain  division  of  the  New  York  series.  These 
reasons  may  be  considered  under  two  heads.  In  the  lirst  place 
is  to  be  mentioned  the  continuity  and  identity  of  this  series 
with  the  Argillite  and  Graywacke  series  iu  western  Vermont 
and  eastern  New  York,  which  had  been  referred  by  Mather 
to  the  Hudson  River  group,  (considered  to  bethestratigraphical 
equivalent  of  ihe  Loraiue  shales)  and  the  Oneida  or  iSiiawaugunk 
formation.  (§  71,  72,  73.)  To  this  was  to  be  added  the  clearly 
expressed  opinion  of  Emmons,  iu  1842,  that  the  green  sand- 
stones examined  by  him  at  Quebec  were  to  be  assigned  to  the 
last  named  formation.     (§  05,  112.) 

§  190.  In  the  second  place  were  to  be  considered  the  facts  ob- 
served in  the  vicinity  of  Quebec,  where  u  nearly  complete  sec- 
tion of  the  series  is  to  be  seen  in  close  proximity  to  the  Tren 
ton  limestone.  In  a  geological  account  of  this  region  by  Dr. 
J.  J.  Digsby,  published  as  early  as  1827,  (Proc.  Geol.  Soc.  I, 
37,)  he  described  the  fossiliferous  limestone  resting  in  a  nearly 
horizontal  attitude  upon  the  ancient  gneiss  on  the  northwest  side 
of  the  St.  Lawrence,  at  Deauport,  while  the  heights  on  both 
sides,  including  the  city  of  Quebec,  Point  Levis,  and  the 
island  of  Orleans,  were  said  to  consist  of  "  a  slaty  series  of 
shales  and  gray  wacke,"  occasionally  passing  into  a  brown  lime 


QRAYWACKE    8EKIE8   OF   QUEBEC. 


E.    9.'. 


stoue,  antl  altomatinu;  with  a  calcareous  cotiujlomerato  in  beds, 
Bonie  of  tliem  charged  with  torisils,  which,  according  to  him, 
were  derived  from  the  horizontal  liuK'stone  of  Beau{)ort.  From 
this  he  concluded  that  the  Graywacke  series,  which  is  highly 
inclined,  is  more  recent  than  the  liniestones.  These  he  sup- 
posed might  belong  to  the  carboniferous  jKjriod,  to  which  also 
he  referred  the  (iraywaclce  series.  This  contains  small  veins 
of  a  bituminous  matter,  regarded  by  him  as  coal,  and  what  he 
supposed  to  be  vegetable  impressions, called  by  him  fucoids,  under 
which  name  two  species  from  this  locality  were  described  by 
Ad.  Brongniart  in  1828,  as  pointed  out  by  Prof.  James  Hall, 
who,  nearly  thirty  years  later,  describtd  and  figured  these  im- 
pressions as  new  forms  of  graptolites.  Geol.  Sur.  of  Canada, 
Decade  II,  page  60,  and  Report  for  1857,  page  111.) 

§  191.  Bigsby 's  view  of  the  greater  antiquity  of  the  Beauport 
limestones  was,  as  we  have  seen,  adopted  as  probable  by  Logan, 
(§  128)  and  was  conlirmed  by  Admiral  Baytield,  who  in  1845 
(Geol.  Journal,  1,  455)  expressed  the  opinion  that  the  Hat  lime- 
stones of  Beauport  and  of  Montmorenci  pass  beneath  the  Gray 
wacke  series.  Ue,  however,  was  aware  that  these  limestones, 
which  had  been  traced,  at  intervals,  along  the  north  side  of  the 
ISt.  Lawrence  to  Montreal,  belong  to  the  Trenton  formation  of 
the  Champlain  division,  and  hence  referred  the  Graywacke 
series,  which  was  still  supposed  to  hold  in  its  conglomerates 
fossils  derived  irom  this  limestone,  to  the  higher  members  of 
that  division.  The  presence  in  the  shales  of  the  Graywacke 
series  in  Gaspe,  of  graptolites,  which  were  supposed  to  be- 
long to  the  Utica  slates,  served  to  conlirm  the  conclusion 
that  the  position  of  this  series  had  been  correctly  determined. 
The  graptolites  of  Point  Levis  were  not  re  discovered  until  1854, 
but  this  locality  had,  as  early  as  1848,  yielded  to  Logan  two 
brachiopodous  shells,  mentioned  by  him  as  "  a  Lcpfnena  very 
like  L.  sericea,  and  an  Orthis  very  like  0.  testudinaria,  and  taken 
by  me  to  be  these  species,"  which  are  characteristic  of  the  upper 
part  of  the  Champlain  division.  (Amer.  Jour.  Science,  [2] 
XXXIII,  106.) 

§  192.  It  is  to  be  noticed  that  a  few  miles  to  the  northeast  of 
Quebec,  rocks  undoubtedly  of  the  age  of  the  Utica  and  Lo- 
raiue  formations  overlie  conformably  the  Trenton  limestone, 


II 


iH 


is 


'4 


96  E. 


Lilil 


SPECIAL    REPORT.      T.  STERRY   HUNT,  1875. 


as  is  seen  on  the  Moiitmorenci  river,  and  beyond,  along  the  left 
bank  of  the  St.  Lawrence;  and  also  tliat  a  few  miles  to 
the  southwest  of  Quebec,  strata  of  these  same  two  forma- 
tions, occupying  similar  stratigraphical  relations,  appear  on 
both  sides  of  the  St.  Lawrence,  and  are  thence  traced  con- 
tinuously to  the  valley  of  Lake  Chami>lain.  These,  moreover, 
oiler  such  lithological  resemblances  to  the  Gray wacke  series  of 
Quebec  and  Point  Levis,  (which,  as  has  been  shown,  extends  for 
hundreds  of  miles  to  the  northeastward,  along  the  right  bank 
of  the  St.  Lawrence,)  that  the  two  series  of  rocks  were  readily 
confounded,  and  thus  the  whole  of  the  belt  of  sedimentary 
strata  along  the  southeast  side  of  the  St.  Lawrence,  from  the 
valley  of  Lake  C'hami)lain  to  Gaspe,  came  to  be  regarded  as 
younger  than  the  limestones  of  the  Trenton  group.  (Hunt, 
Chem.  and  Geol.  Essays,  page  395.) 

§  193.  The  Trenton  limestoiie,  along  the  left  bank  of  the 
St.  Lawrence  near  Quebec,  is  in  many  places  almost  horizontal, 
but  is  affected  by  occasional  anticlinals  running  north-east  and 
south-west,  having  the  stee}tor  dips  on  the  south-east  side. 
These,  in  some  cases,  pass  into  considerable  faults  or  disloca- 
tions, with  downthrows  to  the  southeast.  One  of  them  is  traced 
along  the  southeast  side  of  the  road  from  13eau])ort  church  to 
the  River  Montmorenci,  where  the  disj)lacement  gives  rise  to 
the  well-known  water-fall  of  about  250  feet.  The  Trenton 
limestone,  lying  nearly  flat  at  the  top,  is  seen  at  the  foot  of  tlie 
cascade,  resting,  with  its  edges  upturned,  at  an  angle  of  57° 
against  the  gneiss,  and  dip})ing  to  the  southeast  beneath  a 
conformable  succession  of  beds  of  the  Uticaand  Loraine  shales, 
which  extend  to  the  shore  of  the  St.  Lawrence.  Other  and 
similar  dislocations,  nearly  parallel  with  this,  occur  on  the 
northeast  bank  of  the  St.  Lawrence  above  and  below  Quebec, 
examples  of  which  are  seen  at  Pointe  aux  Trembles  and  at  Stc. 
Anne  de  Beaupr6,  in  which  the  Utica,  in  the  one  case,  and  the 
Loraine  in  the  other,  are  found  leaning,  with  a  high  southeast 
dij),  against  the  gneiss.  (lie[)ort  for  1852,  pages  28-40). 

§  194.  At  a  distance  of  about  eight  thousand  feet  across  the  line 
of  strike  from  the  Heuuport  and  Montmorenci  dislocation, 
against  which  the  Trenton,  Utica  and  Loraine  strata  arc  mnde 
to  dip  southeast  at  a  high  angle,  we  find  rising  from  the  low 


QRAYWACKE    SERIES   OF   QUEHEC. 


E.    97 


57° 
Ith   a 

iind 
the 

ibec, 

Sto. 
the 

I  cast 

lline 

tion, 

liiide 

low 


lands  behind  the  city,  and  from  tlie  waters  of  the  St.  Lawrence, 
the  Graywacke  series  which  forms  the  heights  of  Qnebec,  Sil- 
lery,  Cape  Rouge,  and  Point  Levis,  and  the  island  of  Orleans. 
These  strata,  near  Cape  Rouge,  dip  S.  25°  E.,and  on  tlie  island 
of  Orleans,  S.  E.,  in  both  cases  at  an  angle  of  al)out  50°,  and 
though  affected  by  many  minor  undulations,  have  a  prevailing 
high  inclination  to  the  southeast.  The  thickness  of  the  se- 
lies  here  displayed,  as  measured  by  Logan,  was  estimated  at 
over  5,000  feet,  and  the  sequence  is  essentially  that  previously 
described,  (§  181). 

§  195.  In  1855  was  published  the  Esquisse  Geologiquc,  al- 
ready noticed,  (§  144,)  in  which  (page  80)  the  rocks  of  the 
southeast  side  of  the  St. Lawrence  weredescribed  as  forming  part 
of  a  great  paleozoic  area,  including  also  the  Kew  England 
states,  together  with  Ontario,  New  York,  and  the  whole  of  the 
paleozoic  rocks  to  the  south  and  west.  This  vast  region  was, 
according  to  Logan,  divided  into  two  parts  by  an  anticlinal 
axis,  which,  following  the  Hudson  river  and  passing  to  the 
east  of  Lake  Champlain  and  the  Richelieu  river,  reaches  the 
St.  Lawrence  at  Ueschambault,  about  twenty-five  miles  above 
Quebec.  The  region  to  the  west  of  this,  designated  by  him 
the  western  basin,  includes  the  comparatively  undisturbed 
strata  of  Ontario  and  New  York,  and  the  Appalachian  and 
Michigan  coal-fields ;  while  to  the  east  jf  this  axis  are  found 
the  disturbed  and,  in  part,  crystalline  rocks  already  described, 
which  surround  tiie  coal-tields  of  New  Brunswick  and  Riiode 
Island.  Thisattemj»ted  generalization,  it  will  be  seen,  was  but 
a  repetition  of  that  already  luade  l)y  Mather,  who,  in  1843  had 
already  traced  this  supitosed  axis  from  New  Jersey  nearly  to 
Lake  Champlain,  and  had  asserted  that  the  rocks  on  the  east 
side  of  it  are  nothing  more  than  the  disturbed  and  modified 
equivalents  of  those  on  the  west  (§  G9,  72,  81). 

§  196.  This  anticlinal,  in  its  course  through  eastern  (\anada, 
was  declared  to  Dring  to  the  surface  the  Trenton  limestone  and 
"the  lower  part  of  the  Hudson  river  or  Loraino  shales,"  rest- 
ing upon  which  were  the  rocks  of  Quebec,  Orleans  and  Point 
Levis — now  first  designated  the  Quebec  formation — overlaid 
by  the  red  and  green  shales  and  the  green  sandstones  of  di- 
vision 5,  (§  181)  which,  from  their  occurrence  at  Sil 
7— E. 


^11 

it  I'    -I    . 


I 


98  E. 


SPECIAL    REPORT.      T.  STERRY    HUNT,  1875. 


lery,  were  designated  the  Sillery  formation,  and  declared  to 
correspond  to  the  Oneida  or  Shawangunk  of  Xew  York.  In 
the  geological  map  published  with  the  Esquisse,  these  Quebec 
and  tiillery  formations  were  represented,  respectively,  as  the 
equivalents  of  the  Hudson  River  group  and  the  Otieida  forma- 
tion, and  in  accordance  with  the  views  of  Mather,  the  crystalline 
rocks  of  the  Notre  Dame  Moutains  were  regarded  as  the  al- 
tered equivalents  ot  these  (Esquisse,  pages  40-60). 

§  197.  Thegraptolites  of  Point  Levis  were  first  described  by 
Prof.  James  Hall  in  1855  (Report  for  1857,  page  109).  They 
were  unlike  those  hitherto  known  in  the  Utica  slates  of  the 
Champlain  division,  and  were  regarded  as  belonging  to  a 
higher  horizon — according  to  Prof  James  liall,  "■  that  part  of 
the  Hudson  River  group,  which  is  sometimes  designated  aa 
Eaton's  Sparry  limestone  (§  52), — being  near  the  summit  of  the 
group."  (Ibid,  page  117). 

§  198.  These  rocks  had  been  carefully  traced  by  Logan  from 
Canada  into  Vermont,  and  Ibund  to  include  the  Red  sandrock 
of  that  region,  which  Adams,  in  184(3,  and  W.  13.  Rogers,  in 
1851,  had  already,  in  opposition  to  the  views  of  Emmons,  as- 
signed to  the  summit  of  the  Champlain  division  (§  IIG,  117, 
118).  The  slates  associated  with  the  Red  sandrock  at  Georgia 
in  Vermont  subsequently  yielded  two  species  of  trilobites, 
which  were  described  by  Prof.  James  Hall,  in  1859,  in  the  12th 
Reports  of  the  Regents  of  the  University  of  New  York,  as 
belonging  to  the  genus  Olenus.  These  remains,  subsequently 
referred  by  him  to  a  new  genus,  named  Olencllas,  were  in  1800 
described  by  Emmons  as  species  of  I'aradozides.  That  these 
trik)bites  had  the  characters  belongnig  to  a  much  lower  horizon 
than  that  assigned  to  them  by  Adams,  Rogers,  and  Logan, 
was  well  known  to  Prot^  Hall,  who,  however, described  them  as 
occurring  in  the  Hudson  River  group,  and  in  justification 
thereof  declared  in  anote,  "I  have  the  testimony  of  Sir  AVilliara 
Logan  that  the  shales  of  this  locality  are  in  the  upper  part  of 
the  Hudson    River  group,  or  form  part  of  a  series  of  strata 


listinct  group,  above  the 
Science,  l'2\  XXX  I,  ])p. 


which  ho   is  inclined  to   rank  as  a 
Hudson  River  proper."  (Anier.  Jour, 
213,2:^1).     For  a  farther  history  of  the  question,  see  the  au- 
thor's Chemical  and  Geological  Essays,  pp.  i}9 1-402). 


FAUNA    OF   LEVIS   LIMESTONES. 


E.  99 


§  199.  In  185G  the  present  writer  found,  not  far  from  the 
graptolitic  Rhales  of  Point  Levis,  beds  of  a  bluish-gray  Hrae- 
stono  abounding  in  organic  remains.  These  were  imperfectly 
preserved,  but  among  them  was  a  pygidium  recognized  as  be- 
longing to  an  unknown  trilobito,  which  was  placed  for  exami- 
nation in  the  hands  of  the  late  Mr.  E.  Billings,  (then  recently 
attached  as  paleontologist  to  the  geological  survey  of  Can- 
ada). This  was  the  species  subsequently  described  by  him  as 
Bathyurus  Saffordi.  Farther  explorations  in  18o7,  and  succeed- 
ing years,  brought  to  light  a  large  number  of  species  of  organic 
remains  in  these  and  other  limestone-beds  at  Point  Levis, 
which  Avere  studied  and  described  by  Mr.  Billings. 

§  200.  A  similar  fauna,  though  less  abundant,  was  found  in 
the  limestones  of  Phillipsburg  and  the  adjacent  towns  of  Stan- 
bridge  and  Bedford,  near  Lake  Champlain,  and  also  on  the 
island  of  Newlbundland.  Without  counting  the  graptolitic 
fauna,  there  have  been  got  from  the  limestones  of  these  various 
localities  168  species  of  organic  i-emains,  of  which  seventy-four 
are  crustaceans.  More  than  one-half  of  these  forms  are  met 
with  in  the  limestones  of  I'oint  Levis.  Of  this  considiTa- 
ble  fauna,  according  to  Billings,  five  species  are  known  in  the 
Chazy  limestone,  and  twelve  in  the  Calciferous  sandrock  of  the 
Ottawa  basin,  besides  several  which  are  found  on  the  Upper 
Mississi[)pi,  in  strata  referred  by  Owen  to  the  Potsdam  sand- 
stone, but  not  a  single  species  belonging  to  the  higher  members 
of  the  Champlain  division  ;  while  the  affinities  of  the  new  and 
hitherto  undescribed  species,  are  with  the  lower  rather  than 
with  the  higher  formations  of  the  division.  From  all  these 
facts,  Billings  drew  the  conclusion  that  the  horizon  ])reviously 
assigned  to  these  fossiliferous  strata  by  the  Canadian  survey 
was  not  the  true  ono,  and  that  their  real  position  was  at  the 
base  and  not  at  the  sunnnit  of  the  Champlain  division.  From 
this  it  followed  that  the  Gray  wacke  series  of  Quebec  and  Point 
Levis  was  older  and  not  younger  than  the  Trent(jn  limestone. 
§  201.  These  conclusions  were  unnounced  to  Sir  William  fiO- 
gan  in  a  letter  to  Air.  Barrande,  dated  in  December,  ISGO,  and 
published  in  March,  1801,  (Amer.  Jour.  Science,  [2]  XXXI, 
21G),  when  he  expressed  the  opinion  that  the  Gray  wacke  series 


100    E.  SPECIAL    KEPOUT.       T.  STERRY    HUNT,   1875. 


r. 


..  I 


of  Quebec  was  "  a  great  developraent  of  strata  about  tbe  bori- 
zon  of  tbe  Cbazy  and  tb(!  Calciferous,  brougbt  to  tbe  surface 
by  an  overturn  anticlinal  fold,  witb  a  crack  and  a  great  dislo- 
cation running  along  tbe  summit,"  by  wbicb  tbe  rocks  in  ques- 
tion (liencefortb  called  tbe  Quebec  grouj;),)  "were  brougbt  to  over- 
lap the  Hudson  River  formation."  He,  at  tbe  same  time,  de- 
clared tbat  "  from  tbe  j)bysical  structure  alone,  no  person 
would  suspect  tlie  break  tbat  must  exist  in  tbe  neigbborbood 
of  (Quebec  and,  witbout  tbe  evidence  of  fossils,  every  one  would 
be  authorized  t(j  deny  it."  Logan  was  tbu.s  led  by  tbe  paleon- 
tological  evidence  furnisbed  by  Billings  to  adopt  tbe  conclu- 
sion as  to  tbe  age  of  these  rocks  whicb  bad  been  maintained 
by  Emmons  since  1846,  wben  the  latter  declared  tbat  tbe  series 
wbicb  be  bad  previously  referred  to  tbe  Hudson  River  group, 
in  eastern  New  York  and  Vermont,  was  a  modification  of  tbe 
Calciferous  sandrock,  protean  in  character,  and  including  a 
great  mass  of  sandstones,  shales  and  limestones  (§  95,  90,  98). 
This  priority  on  tbe  part  of  Emmons  was  thus  statod  by  Lo- 
gan in  the  letter  above  cited,  "Prof.  Emmons  bas  long  main- 
tained, on  evidence  wbicb  bas  been  much  disputed,  tbat  rocks 
in  Vermont  whicb,  in  June  last,  I,  for  the  first  time  saw,  and 
recognized  as  equivalent  to  the  magnesian  part  of  the  Quebec 
group,  arc  older  than  the  Birdseye  formation  (tlie  basal  beds 
of  the  Trenton).  The  fossils  wliicb  have  this  year  been  ob- 
tained at  Quebec  pretty  clearlj*  demonstrate  tbat  in  this  he  is 
right  " 

§  202.  These  were  the  rocks  which  Emmons  described,  in 
1840,  as  superior  to  the  Granular  quartz-rocK,  the  Stockbridge 
limestone,  and  tbe  Magnesian  slate  (wbicli  constitute  the  lower 
portion  of  his  Taconic  s\'stem,)  and  included  under  the  general 
name  of  the  Taconic  slates  (§  103).  It  was  tliese  wliicb,  in 
1855,  he  separated  from  tbe  lower  members  and  distinguished 
by  tbe  name  of  Ui>per  Taconic.  This  latter  division  be  de- 
clared to  contain,  in  its  ui)per  portions,  tbe  remains  of  grapto- 
lites,  fucoids  and  crustaceans  (§  104,  107).  Although  at  an 
earlier  date  Emmons  bad  spoken  of  bis  Taconic  system  as  in- 
ferior to  the  whole  of  the  Champlain  division,  this  view  was 
subsequently  confined  to  the  Lower  Taconic,  since  the  Upi)er 


THE  QUEBEC  OR  UPPER  TACONIC  GROUP. 


E.    101 


ob- 


,  in 


i( 


Ige 


iwer 
oral 
I,  ill 
;he(l 
(le- 
|pto- 
an 
in- 
[was 
L)er 


Taconic,  as  defined  in  his  Ainerican  Geology,  included  not  only 
"the  modified  and  protean  Calcil'erous  sand-rock,"  but  tlie  Pots- 
dam itself  (§  114).  It  is  apparently  by  one  of  those  inconse- 
quences already  noticed  (^§  U3)  that  in  the  same  work,  in  his 
account  of  the  Granville  section  (§  108)  he  makes  the  Taconic 
slates  to  underlie  the  Calciferous  sandrock.  To  Emmons  un- 
doubtedly belongs  the  credit  of  having  first  discovered  tiie 
true  horizon  of  these  Upper  Taconic  rocks,  which  was  sub- 
sequently established,  independently,  by  the  paleontological 
studies  of  Billings. 

§  203.  Logan,  however,  as  we  have  seen,  did  not  adopt  for 
tliese  rocks  the  name  of  Upper  Taconic,  which  liad  been  pre- 
viously given  them  by  Emmons.  Keferring  to  the  description 
of  the  Graywacke  series  given  in  §  181,  it  will  be  remembered 
that,  in  1855,  the  rocks  there  included  in  division  5  had  been 
called  the  iSillery,  while  divisions  1-4  had  been  designated  the 
Quebec  formation.  Eor  the  latter,  the  name  of  Levis  was  now 
substituted,  and  these,  together  with  the  Sillery,  were  called, 
in  Logan's  letter  to  Barrande,  the  Quebec  group;  of  which  a 
section,  with  measurements,  as  displayed  in  the  island  of  Or- 
leans, was  first  given  in  the  Geology  of  Canada  (18G3),  page 
227.  In  the  Report  of  18G3-6G  (page  41),  for  greater  con- 
venience in  tracing  out  the  supposed  parallelism  between  these 
strata  and  the  crystalline  rocks  of  the  Notre  Dame  range,  there 
was  established  a  third  division  in  the  Quebec  group,  by  giv- 
ing to  its  middle  portions  the  name  of  the  Lauzon  formation, 
taken  from  the  seigniory  of  that  name,  in  which  I'oint  Levis  is 
situated. 

§  204.  The  Levis  formation,  as  thus  limited,  included  divi- 
sions 1-9  of  the  Orleans  section  (above  rel'erred  to)  comprising 
1,285  feet  of  green  and  gray  shales,  often  dolomitic,  together  with 
some  sandstones,  limestones  and  conglomerate  layers.  About 
midway  in  this  formation  is  a  belt  of  gray  argillaceous  shales 
holding  Pliyllograpliis  typus  ;  while  other  organic  forms,  obscure 
and  undetermined,  occur  in  calcareous  beds,  both  above  and  be- 
low this  belt. 

The  Lauzon  formation,  including  tiie  divisions  10-17  of  the 
Orleans  section,  n»easures  3,740  feet,  and  consists,  like  the  pre- 
vious one,  of  sandstones,  conglomerates  and  shales,  in  winch 


:• 


'r  I 


I   ff' 


i 


I 


i 

I  hi 


i 


1 02  E. 


SPECIAL  REPORT.      T.  STERRY  HUNT,  1875. 


red  and  purple  colors  often  })revivil,  especially  towards  the  sum- 
mit, where  is  a  mass  of  1,000  feet  or  more  of  red  shales,  well  seen 
at  Cape  Rouge,  in  which  occur  a  species  of  Lingula  and  Oholella 
preMosa.  Near  the  hase  of  the  Lauzon  are  several  hundred  feet 
of  soft  shaly  sandstones,  containing  in  parts,  abundant  green 
grains  of  glauconite,  analyses  of  which  will  be  found  in  the 
Geology  of  Canada,  page  486. 

§  205.  To  the  Lauzon  succeeds  the  Sillery  formation,  not 
seen  in  the  Orleans  section,  consisting  of  greenish,  drab- weath- 
ering sandstones,  colored  by  chloritic  matter,  and  holding  scales 
of  mica  and  of  graphite,  together  with  small  fragments  of 
green  and  black  slates, often  calcareous,  and  becoming,  in  some 
layers,  a  quartzose  conglomerate.  These  sandstones,  like  the 
beds  of  the  two  formations  just  described  on  Orleans  Island,  dip 
to  the  southeast  at  an  angle  of  about  50°.  Mr.  Billino-s  united 
with  the  Sillery  the  mass  of  red  shales  assigned  by  Logan  to 
the  summit  of  the  Lauzon,  which  contain  in  two  localities  the 
Oboldla  named,  and  are  interstratilied  with  the  green  sand- 
stones, from  which  they  cannot  he  separated.  (Paleozoic  Fos- 
sils, Vol.  I,  pages  62,  69.)  The  thickness  of  these  sandstones 
was  by  Logan  estimated  at  2,000  feet,  making  the  total  volume 
of  the  Quebec  group,  as  defined  by  him,  a  little  over  7,000  I'ect. 

The  lithological  and  chemical  characters  of  these  green  chlo- 
ritic sandstones  of  the  Sillery  formation  have  already  been 
described.     (§  183,  184.) 

§  206.  It  is  noteasy  to  identify  the  different  sub-divisions  of 
the  Orleans  section,  either  in  the  city  of  Quebec  or  at  Point  Levis. 
Much  interest  attaches  to  the  latter  locality,  because  it  is  there 
that  have  been  obtained  the  organic  remains  which  have  been 
relied  upon  to  fix  the  geological  horizon  of  the  Quebec  group. 
It  will  be  well,  in  the  fi.r8t  place,  to  consider  some  of  the  litho- 
logical peculiarities  of  the  strata  here  met  with,  as  described 
by  the  present  writer  in  1856. 

The  rocks  at  Point  Levis  present  interstratifications  of  pure 
limestones,  dolomites,  sandstones  and  argillaceous  shales. 
"  Both  limestones  and  dolomites  are  very  irregular  and  inter- 
rupted in  their  distribution,  the  beds  sometimes  attaining  a 
considerable  volume,  while  atother  times  they  thin  out, orare  re- 
placed by  sandstones.     The  limestones  freciuently  form  masses  of 


ill 


LIMESTONES   AND   DOLOMITES   OF  LEVIS.        E.    103 


many  feet  in  thickness,  which  are  without  visible  marks 
of  stratification,  and  destitute  of  organic  remains.  These 
masses  are  compact,  conclioidal  in  fracture,  sub-translucent, 
and  exhibit  a  banded  agatized  structure,  which  leads  to  the 
conclusion  that  they  are  chemical  deposits  from  water — in 
fact,  veritable  travertines.  Their  colors  are  pearly  grey  of 
different  sliades,  and  occasionally  pale  green  ;  they  weather 
smooth  and  wliite.  Analysis  shoAvs  that  they  are  pure  car- 
bonate of  lime,  and  contain  neither  silica,  iron,  nor  magne- 
sia, in  appreciable  quantities.  Interstratilied  with  these 
travertines,  however,  there  are  beds  of  tine  granular  opa(pie 
limestones,  weathering  bluish-grey,  and  holding,  in  abund- 
ance, remains  of  othoceratites,  trilobites,  and  other  fossils, 
which  are  rejilaced  by  a  yellow- weathering  dolomite. ' '  These 
have  been  already  noticed  in  §  199. 

§  207.  "The  dolomites  occur  both  among  the  travertines 
and  the  fossiliferous  limestones,  sometimes  in  small  lenticu- 
lar masses,  or  in  layers  of  a  few  lines,  interposed  in  nuisses 
of  limestone.  At  other  times  the  layers  of  dolomite  are 
several  feet  in  thickness,"  Unlike  the  associated  lime- 
stone, the  dolomites  contain  an  admixture  of  sand  and  clay, 
and  from  live  to  ten  per  cent,  of  carbonate  of  iron,  wliich 
causes  them  to  weather  reddish-brown.  They  are  slightly 
bituminous,  and  include  grains  of  pyrites  and  veins  of  cal- 
cite,  but  were  never  found  to  contain  fossils,  and  often  pass 
into  a  dolomitic  sandstone,  with  rhombohedral  cleavages, 
due  to  the  crystalline  matrix.  In  one  example,  a  com])act 
ferriferous  dolomite  contained  half  its  weight  of  claj'ey 
matter.  It  is  chiefly  these  mag;nesian  beds  which  become 
conglomerate.  "In  addition  to  sand  and  clay,  the  dolomites 
frequently  enclose  grains  and  rounded  fragments  of  lime- 
stone and  of  dolomite,  ])oth  seemingly  derived  from  adja- 
cent strata,  so  tiiat  we  have  beds  consisting  of  pebbles  of 
limestone,  often  having  the  characters  of  the  travertine,  of 
dolomite,  and  occasionally  of  quartz  and  of  argillite,  the 
whole  cemented  by  a  ferriferous  dolomite.  At  other  times 
the  cement  of  the  conglomerate  is  a  ncaily  pure  carbonate 
of  lime."     (Report  for  ISoB-SO,  pages  464-466).     These  im- 


m 


li!  \ 


104   E.       SPECIAL   REPORT.      T.  STERRY  HUNT,  1875. 

bedded  fragments  of  argillite  are  purplish  or  gi-eenish  in 
color,  lustrous,  and  sometimes  apparently  chloritic. 

§  208.  Some  of  tlie  finely  granular  gray  limestones  above 
described,  which  contain  small  patches  and  layers  of  yel- 
lowish dolomite,  and  moreover  hold  organic  remains  re- 
placed by  the  same  material,  have,  although  in  nowise  con- 
glomerate in  their  t)rigin,  an  aspect  which  suggests  the  con- 
glomerates already  noticed,  and  have  often  been  mistaken 
for  them.  Such  is  the  nature  of  some,  at  least,  of  the  cal- 
careous bands  which  have  yielded  the  organic  remains  at 
Point  Levis.  BathyuriLS  Saffordi.,  a  typical  species,  was 
first  found  in  abed  of  compact  limestone,  not  conglomerate, 
and  Logan  satisfied  himself,  as  he  tells  us,  that  the  fossils 
collected  by  him  are  of  the  age  of  the  strata.  Certain  of 
the  forms  there  obtained,  he  afterwards  thought,  might  be 
included  in  masses  derived  from  older  strata,  but  he  de- 
clared, in  accordance  with  the  views  above  expressed,  that 
"some  of  the  fossiliferous  porticjns  of  the  Point  Levis  bands, 
having  the  same  color  and  texture  as  the  supposed  boulders, 
possess  the  character  of  original  sediments,  or  of  concre- 
tionary masses,  and  it  is  difficult  to  separate  the  fossils  of 
these  from  those  of  the  rolled  masses."  (Geology  of  Can- 
ada, page  8G0. ) 

§  209.  The  strata  of  Point  Levis  contain  two  unlike  fau- 
nas, which  are  found  in  unlike  rocks,  and  in  localities  en- 
tirely distinct  from  one  another.  We  have,  in  the  first 
place,  a  series,  chiefly  of  argillaceous  shales,  abounding  in 
graptolites  ;  and  in  the  second,  a  series  of  bands  and  len- 
ticular masses  of  limestone,  sometimes  apjiarently  conglom- 
erate, which  hold  a  remarkable  trilobitic  fauna,  and  are  in- 
terstratified  with  sandstones,  and  with  shales  which  are 
distinct  from  those  mentioned  above,  and  have  yielded  no 
graptolites.  Both  of  these  Avere,  however,  by  Logan,  in- 
cluded in  the  Levis  division  of  the  Quebec  group.  The 
distinction  between  these  two  fossiliferous  formations  is  not 
made  clear  in  the  Geology  of  Canada  (page  8C1),  where 
these  rocks  are  briefly  described.  The  plan  of  Point  Levis, 
there  referred  to,  however,  which  is  published  in  the  Atlas, 
and  is  on  a  scale  of  three  inches  to  a  mile,  shows  the  course 


i 


GRAPTOLITIC   SUALES   OF  LEVIS. 


E.    105 


of  every  band  of  limestone,  the  outcrops,  and  the  various 
localities  from  which  fossils  have  been  collected.  "With 
this,  and  its  accompanying  section,  aided  by  the  description 
given  in  the  letter  of  Logan,  (§  2ul,)  the  following  state- 
ment of  the  relations  of  these  rocks  will  be  intelligible : 
The  strata  at  Point  Levis,  with  a  high  south-east  dip,  rise 
rai)idly  from  the  shore  of  the  St.  Lawrence,  which  is  paral- 
lel to  their  strike,  and  form  a  succession  of  bold  ridges,  at- 
taining a  height  of  400  feet  or  more,  across  which,  by  a 
series  of  undulations,  the  limestones,  congh)merates,  and 
shales  (^f  the  Quebec  group  are  distributed  over  a  breadth 
of  more  than  two  miles  transverse  to  the  strike.  In  this 
distance  they  exhibit  two  well-marked  iinticlinals,  with  in- 
dications of  a  third.  The  intermediate  synclinals  are  sharp 
and,  according  to  Logan,  are  overturned,  so  that  the  strata 
on  both  sides  dip  steeply  to  the  south-east. 

§  210.  Near  the  lower  ferry  at  Point  Levis  is  a  cliff  about 
100  f'jet  high,  composed  of  shales,  with  thin-bedded  lime- 
stone and  some  conglomerate  layers,  the  whole  dipping  to 
the  south-east  at  a  high  angle.  The  strata,  whi(;h  are  dark 
gray,  and  very  tender,  abound  in  graptolites  and  related 
forms.  Prof.  James  Ilall  has  described  from  this  locality 
not  less  than  forty-two  species,  which  are  thus  divided 
among  the  following  genera  :  Graptolilhus^  25  ;  Retlolites^ 
1;  lldeograptus^  2;  PJu/Ilograj)tus,  5 ;  DendrograpLas^ 
3  ;  TJiaiiinograptus,  3 ;  Didijom.ma^  3.  With  these  were 
found  species  of  brachiopods  described  by  Billings  under 
the  names  of  Lingula  Irene,  L.  Quebecensis,  and  Ohol- 
ella  desiderata,  besides  an  Ortliis  and  n >Strop)honiena,  both 
undescribed,  and  in  the  accompanying  limestone  an  un- 
named Tetradlum,  a  minute  trih)l)ite,  which  was  desciihed 
under  the  name  of  Shumardia  granulosa,*  and  another 
undescribed,  which  was  i-eferred  to  Dikellocephalus. 

§211.  Leaving  this  belt  of  fossiliferous  strata,  we  ascend 
the  coast  ridge,  and  reach  what  is  describ'd  on  the  plan  as 
the  middle  ridge.     Here,  at  a  point  of  about  five  eighths  of 


HI! 


*This,  by  a  typographireil  error  in  the  Geology  of  Canada,  (page  8(54)  is 
plaood  ill  oolnnin  I,  instead  of  A,  where  it  belongs.  See  Billings,  Paloow>ic 
Fossils,  page  93. 


« 


100  E.     SPECIAL  KKi'oirr.     t.  8TKKi:v  hint,  1876. 

a  mile  east  of  tlie giaptolitic  shales,  and  three  eighths  of  a 
Tiiile  across  the  strike  from  the  line  of  these,  we  find  the 
iirst  of  the  limtjstone  beds  with  the  trilobitic  fauna,  which 
is  coiitinfMl  to  certain  limestone  bands  marked  on  the  plan, 
(and  in  tiie  Geology  of  Canada,)  2-8,  numbering  to  the 
south-east ;  the  whole  occupying  a  breadth  of  less  than  a 
quarter  of  a  mile  across  the  strike. 

Not  one  of  the  fifty  species  found  in  the  graptolitic  zone 
to  the  north-west  has  been  here  met  with,  and,  with  the 
excejDtion  of  an  undescribed  Dlctyonema,  not  a  single  spe- 
cies belonging  to  the  order  of  the  Graptolitidea?.  The 
species  from  these  limestones  catalogued  by  Mr.  Billings, 
are  103  in  number,  of  which  69  have  been  described.  Pass- 
ing over  the  long  list  of  brachiopods,  gasteropods,  cepha- 
lopods,  etc.,  we  find  not  less  than  31  descril^ed  species  of 
trilobites,  divided  as  follows  among  the  genera  named  : 
Af/nosius,  3 ;  Amjjliiori^  1;  AriuneUiis,  2 ;  Asaphus^  2 ; 
Bathyurns^  8;  Cheirurus ;  ConocejjJiaUies  {Conocorphye,) 
1 ;  DlJielloceplialits,  7 ;  Eiidymioji,  1 ;  Holometopus^  1; 
Menocephahis^  3;  besides  one  each  of  JVileus,  Amj^yx,  and 
Jllanus,  undescribed.  Of  these,  the  last  two  named  are 
found,  with  J/oJomelopvs,  only  in  bands,  while  one  species 
of  Batliyurua  occurs  in  band  2  ;  all  the  others  being  confined 
to  the  bands  3  and  4,  and  often  common  to  the  two.  These 
contiguous  bands  weie,  by  Logan,  regarded  as  the  same 
one,  repeated  by  a  dislocation  or,  as  he  afterwards  sup- 
posed, by  an  overturned  synclinal  fold. 

§  212.  A  few  of  the  organic  remains  found  at  Point 
Levis  have  been  observed  on  the  island  of  Orleans,  but  it  was 
conceived  by  Logan  that  both  the  graptolitic  and  the  tri- 
lobitic zone  were  included  in  the  iirst  ten  divisions  (measur- 
ing about  2,000  feet)  of  the  Orleans  section,  in  which  he  did 
not  attempt  to  iix  the  relative  positions  of  the  two  fossil- 
iferous  horizons.  He  however  noticed  (Geol.  Canada, 
page  280)  that  the  argillites  between  the  limestone  bands 
at  Point  Levis  often  include  red  layers,  in  which  respect 
they  differ  from  the  lower  portion  of  the  Orleans  section, 
designated  the  Levis  formation;  while,  on  the  contrary,  the 
upper  part  of  that  section,  referred  to  the  Lauzon,  has  red 


FOSSILIFEUOUS    LIMESTONES   OF    LEVIS. 


E.    107 


argillite  bands  at  several  horizons;  thus  niakinf^  it  proV)able 
that  a  large  portion  of  the  Levis  section  belongs  to  the  so- 
called  Lanzon.  It  will  be  remembered,  however,  that  a 
thick  band  of  argillaceous  shales,  holding  PlnillorfraptuSy 
and  the  supposed  equivalent  of  the  graptolitic  zone  at 
Point  Levis,  is  found  in  the  Orleans  section,  about  700  feet 
from  its  base. 

§  213.  Billings  published  his  first  account  of  the  fauna  of 
these  limestones  in  the  Canadian  Naturalist,  in  August, 
1860,  and  Barrande,  commenting  thereon,  in  1801,  (Bull.  Soc. 
Geol.  de  Fi'ance,  2me  sdrie,  tom.  XVIIl,  page  203,)  called  at- 
tention to  the  fact,  tliat  while  the  limestones  of  band  3  (No. 
1  of  Billings)  had,  at  that  time,  yielded  triiobites  of  the  ge- 
nera, Arwnellu.s,  Dikellocephahis,  Menocejplialus,  and  Von- 
ocoryphe^  the  band  4  (No.  2  of  Billings)  contained  none 
of  tliese,  but  only  Bathyurus  and  A(/nostys,  witli  Chei- 
riirus.  This  latter  genus,  together  with  associated  lirach- 
iopods  and  species  of  Orthoccras  and  Ci/rtoccra-s,  lead  him 
to  refer  the  band  4  to  his  second  fauna;  wliile  the  band  3, 
according  to  Barrande,  belonged  clearly  to  the  first  or  i)ri- 
mordial  fauna.  Subsequently,  liowever,  Billings  found  Or- 
thoceras  in  3,  while  two  species  of  DikeUocepJialus  were  de- 
clared to  be  common  to  3  and  4,  and  he  was  led  to  believe, 
with  Logan,  that  the  two  bands,  if  not  identical,  belong 
to  the  same  liorizon,  and  present  an  admixture  of  forms 
belonging  to  the  two  faunas. 

§  214.  At  a  later  date,  in  1863,  Billings  expressed  the  opin- 
ion that  the  forms  at  first  described  by  him  as  species  of 
Arionellus,  sliould  be  referred  to  tlie  new  genus  Ftychaspis 
of  Hall,  from  the  western  Potsdam,  which  would  also  in- 
clude one  of  the  Levis  species  previously  called  a  Dikello- 
ceplialus.  A  new  genus,  LogaiielluH^  proposed  by  Devine 
for  a  trilobite  from  Point  Levis,  at  first  referred  to  Olenus^ 
will  include,  according  to  Billings,  other  species  of  the  so- 
called  Dikdlocephaliis^  as  well  as  some  of  the  western  forms 
referred  by  Shumard  and  ])y  Hall  to  Conoceq^halile.s.  Bill- 
ings now  expressed  th*^  opinion  that  the  Levis  belonged  to 
a  somewhat  later  pei-iod  tlian  that  of  the  lai'ge  si)ecies  of 
Paradoxides,  and  declared  that  we  have,  in  the  Levis  lime- 


Hi 


!ii 


108   E.      SPECIAL    RKPOKT.      T.  STERRY  HUNT,  1875. 

stone,  "  the  leadin<^  generic  types  of  the  dominant  family  of 
the  Potsdam  trilobites."  (Pal.  Fossils,  pages  198-200.)  This 
was  in  accordance  with  the  declaration  by  Professor  Ihill, 
in  1801,  that,  judging  from  its  trilobitic  fauna,  the  Levis 
limestcme  "is  in  parallelism  with  the  Potsdam  and  Calcif- 
erous  strata."    {American  Journal  Science,  [2,j  xxxi.,  222.] 

§  215.  The  rocks  now  included  in  the  Quebec  or  Hudson 
River  group  by  Logan,  were,  however,  found  to  contain  still 
another  fauna,  which  included  the  two  species  of  Olenellus 
described  by  Hall  from  Georgia,  Vermont,  (§  198.)  The  Red 
sandrock  of  that  vicinity  has  also  yielded  two  species  of  Con- 
ocorifphe  and  an  OholeUa,  besides,  according  to  Perry,  crin- 
noidal  stems.  Subsequently,  these  same  species  of  Olen- 
ellus, together  with  the  ConocorypJie,  were  discovered  in  a 
limestone  at  Forteau  Bay,  on  the  north  side  of  the  strait 
of  liel lisle,  with  three  species  of  Bathyurus,  Sallerella,  and 
ArcJieocyathus,  besides  numerous  brachiopods,  including 
the  Oholella  found  in  the  Red  sandrock  of  Vermont.  These 
limestones,  associated  with  red  and  green  shales,  have  an 
observed  thickness  of  143  feet,  and  overlie  conformably  a 
mass  of  nearly  liorizontal  red  and  grey  sandstones,  often 
conglomerate,  which  rest  upon  Laurentian  gneiss,  and  are 
made  up  of  its  ruins.  Many  beds  of  these  sandstones,  which 
have  an  aggregate  thickness  of  231  feet,  are  penetrated  ver- 
tically by  ScolilJius  linearis. 

%  216.  On  the  opposite  side  of  the  strait  of  Bellisle,  which 
is  here  from  ten  to  fifteen  miles  in  width,  appears  a  belt  of 
paleozoic  rocks,  stretching  thence  along  the  north-west  side 
of  the  island  of  Newfoundland  for  a  distance  of  180  miles 
to  the  south-west.  It  is  limited  to  the  south-east  by  a  par- 
allel range  of  crystalline  rocks,  in  part  Laurentian. 

Akmg  the  shore,  this  belt  of  sedimentary  strata  lies  nearly 
horizontal,  but  where  we  can  examine  the  strata  to  the  south- 
east, across  the  strike,  as  at  Pistolet  Bay,  which  is  at  the 
north-east  extremity  of  the  island,  and  at  Bonne  Bay,  180 
miles  to  the  south-west,  they  are  found  to  be  greatly  dis- 
turbed, faulted,  and  often  inverted  as  we  approach  the  crys- 
talline range.  This  region  was  examined  by  Mr.  James 
Richardson,  in  1801  and  1802,  and  from  his  notes  and  col- 


STRAIT   OF    BELLISLE,   NEWFOUNDLAND. 


E.    109 


lections  the  officers  of  the  Canada  Survey  prepared  the  de- 
scriptions given  in  the  Geology  of  Canada,  (pages  287-21)3, 
and  804-880.) 

§  217.  The  arrangement  of  these  rocks  on  the  two  sides 
of  the  strait  of  Bellisle  is  supposed  to  be  tliat  of  a  sliallow 
synclinal.  A  series  of  beds  on  the  island,  chietly  of  sand- 
stones and  niagnesian  limestones,  believed  to  follow  the 
beds  already  noticed  on  the  mainland,  and  making,  with 
these,  a  total  thi(;kness  estimated  at  1,147  feet,  was  de- 
scribed under  the  name  of  the  Potsdam  group.  Succeeding 
these  are  not  less  than  3,200  feet  of  limestones  which,  from 
their  organic  remains,  were  referred  to  the  Calciferous  for- 
mation. To  this  succeed  1,400  feet  of  limestones,  often 
conglomerate,  with  black  shales,  supposed  to  belong  to  the 
Levis  formation,  which,  at  that  time,  included  the  Lauzon 
division.  (§  203.)  These  rocks,  along  the  north-eastern 
part  of  the  belt,  present  very  slight  inclinations  to  the 
south-east,  but  farther  to  the  south-west,  where  the  crys- 
talline range  is  nearer  the  shore,  they  are  affected  by  un- 
(lulati(ms  running  north-east  and  south-west,  and  are 
highly  inclined  to  the  south-east,  and  sometimes  even  ver- 
tical in  altitude. 

§  218.  At  the  south-western  extremity  of  the  belt  exam- 
ined, where  Bonne  Bay  affords  a  transverse  section,  there 
is  found  a  series  of  blackish-blue  argillites,  with  transverse 
slaty  cleavage,  interstratified  with,  and  underlaid  by  gray 
quartzites.  This  group,  with  a  thick];  3ss  of  GOO  feet,  and 
without  observed  fossils,  is  followed  by  a  series  of  lime- 
stones with  shales  and  sandstones,  estimated  at  1,400  feet, 
holding  organic  remains  like  those  of  the  Labrador  coast, 
and  hence  referred  to  the  Potsdam  group.  Other  fossil- 
iferous  strata  of  the  series  occur  in  the  neighborhood,  but 
"they  are  much  contorted,  and  it  is  dilTicult  to  make  out 
the  true  succession."  Overlying  these,  in  conformable 
sequence,  appear  2,000  feet  of  greenish  sandstones  and 
shales,  referred  to  the  Sillery  formation,  the  whole  dipping 
south-east  at  angles  of  from  45°  to  80° ;  while  further  to  the 
south-east,  across  an  arm  of  the  bay,  rises  a  mountain  of 
serpentine,  with  talcose  slates,  more  than  2,000  feet  in  height. 


iVi 


tr 


110  E.      SPECIAL   REPORT       T.  STERRY  HUNT,  1875. 


^1 

2:  It 


'H. 


j     t[ 


§  219.  At  Cape  Norman,  at  the  north-easi  extremity  of 
Newfoundland,  most  of  these  fossiliferous  strata  appear,  at 
first  witli  moderate  dii)8  to  the  soutli-east,  but,  in  tliat  direc- 
tion, soon  become  affected  by  great  undulations,  and  are 
o+'ten  vertical  or  even  overturned  along  the  west  shore  of 
Pistolet  Bay,  where  the  fossiliferous  limestones  and  slates 
are  seen,  devoid  of  any  crystalline  character.  On  the  east 
side  of  the  same  bay,  is  a  mass  of  hornblendic,  feldspathic, 
and  chloritic  rocks,  interstratiiied  with  serpentine  and  dial- 
lage-rock,  the  whole  estimated  at  about  1,200  feet  in  thick- 
ness. Succeeding  these,  on  the  south-east  side,  is  a  great  de- 
velopment of  chloritic  sandstones  and  conglomerates,  which 
(jccupy  a  breadth  of  several  miles,  and  are  supposed  to 
rei)resent  the  Sillery  formation ;  which  here  occurs,  not  be- 
tween the  fossiliferous  sediments  and  the  serpentines,  as  at 
Bonne  Bay,  but  separated  from  the  former  by  a  mass  of  sim- 
ilar serpentines.  The  rocks  in  Pistolet  Bay  are  ailecred  by 
four  dislocations,  one  of  which  is  supposed  to  be  a  down- 
throw^ of  about  1,400  feet  to  the  south-east  side,  "while  the 
other  three  are  up-throws  to  the  south-east."  Several  other 
similar  dislocations,  running  with  the  strike,  or  nearly  so, 
are  observed  further  south-west,  towards  Bonne  Bay,  "all 
of  them  being  up-throws  on  the  south-east  side."  (Geol. 
Canada,  page  87G.) 

§  220.  After  a  further  and  careful  study  of  the  collection 
of  fossils  from  these  Newfoundland  rocks,  Billings  declared 
that  the  chai";cteristlc  fauna  of  the  Levis  limestones  (found 
also  at  Phillipsburg  and  Bedford,  near  Lake  Champlain) 
had  been  met  with  in  Newfoundland,  only  at  Cow-Head,  a 
point  not  far  from  the  south-west  extremity  of  the  belt  of 
fossiliferous  strata.  He  also  recognized  a  series  of  beds 
holding  the  organic  remains  of  the  typical  Calciferous  sand- 
rock  of  the  Champlain  division.  These  strata,  however,  if 
we  may  trust  the  observations,  do  not  immediately  underlie 
the  Levis  limestones,  but  are  separated  from  them  by  more 
than  2,000  feet  of  limestones  containing  a  fauna  distinct 
alike  from  the  Calciferous  and  the  Levis.  While  including 
some  si)ecies  belonging  to  the  Cliazy.  and  others  very  simi- 
lar to,  if  not  identical  with  those  of  the  i^Iack  Kiver  nn<l 


CnAMPLAIN   DIVISION   IN   NEWFOUNDLAND.     E,    111 


Trenton  limestones,  most  of  tlie  typical  species  of  these  for- 
mations of  the  Champlain  division  are  wanting.  These  in- 
termediate strata  were  subsequently  distinguished  by  the 
name  of  Upper  Calciferous.  ''It  would  thus  appear,"  in 
the  language  of  Mr.  J3illings,  ''  tluit  the  Levis  limestones  are 
at  least  2,UU0  feet  above  the  true  Calciferous  sand-rock. 
That  so  many  trilobites,  belonging  to  the  dominant  type  of 
the  Potsdam  period,  should  occur  in  sucli  a  horizon,  np])oars 
to  be  a  most  extraordinary  fact.  Judging  from  the  fossils 
alone,  I  should  say  that  the  Levis  immediately  succeeds  the 
Calciferous,  but  the  physical  evidence  seems  to  show  that 
this  is  not  the  case."  (Paleozoic  Fossils,  vol.  I,  irdges  66- 
207,  and  371-377.) 

§  221.  Beneath  the  strata  regarded  as  the  representative 
of  the  true  Calciferous  sandrock,  which  consist  of  lime- 
stones and  geodiferous  dt)lomites,  are  found  beds  holding 
Lingida  acuminata,  overlying  a  series  of  white  sandstones 
and  conglomerates,  which  contain,  besides  quartz  pebbles, 
numerous  worn  fragments  of  blackish  argillite.  These  beds 
were  regarded  as  equivalent  to  the  typical  Potsdam  sand- 
stone of  central  Canada  and  northern  New  York,  and  were 
designated  by  Billings  as  the  Upper  Potsdam,  while  the 
name  of  Lower  Potsdam  was  given  to  the  basal  beds  on  the 
Labradox'  coast,  and  those  near  Bonne  Bay,  containing 
Olencllus,  Gonocoryphe,  Obolus,  Salterclla,  Archeocf/athus, 
etc.  To  this  was  also  referred  the  Red  sandrock  of  Ver- 
mont and  its  associated  slates,  and,  subsequently,  tlie  strata 
holding  a  similar  fauna  from  Troy,  New  York,  which,  ac- 
cording to  Ford,  rest,  like  tlie  R'ld  sandrock  (§  116,)  inap- 
l^arent  conformity  upon  the  ui)per  members  of  the  Cham- 
plain  division,  the  whole  succession  dipping  to  the  east- 
ward.    (American  Journal  Science  [3]  VI,  134.) 

§  222.  The  nomenclature  thus  adopted  for  these  rocks  was, 
in  ascending  order :  1°,  Lower  Potsdam  ;  2^,  Upper  Pots- 
dam ;  3°,  Lower  Calciferous  ;  4°,  Upper  Calciferous  ;  5*, 
Levis;  6°,  Lauzon ;  7",  Sillery.  The  formntions,  2  and 
3,  in  this  series  were  regarded  as  the  ('(|iiival('ii(s  of  the 
typical  PotscJMm  sandstone  and  the  Calciferous  sandrock  of 
the  Champlain  division,  (Report,  1806-^61),  page  236).   At  tlie 


112   E.       SPECIAL   REPORT.       T.  STERRY  HUNT,   1875. 


same  time  the  strata  from  St.  John,  in  New  Brunswick,  and 
from  St.  John's,  in  south-eastern  Newfoundland,  which  con- 
tain, besides  Conocoryphe  and  Ar/nosiiis,  species  of  Para- 
doxUles  and  Mktrodlscus,  were  referred  to  a  still  lower  hori- 
zon, under  the  name  of  the  St.  Jolin's  group,  which  is  un- 
doubtedly equivalent  to  some  part  of  the  Lower  Cambrian 
of  Wales.  To  this  hoi-izon  also  belong  the  Paradox  ides 
beds  of  Braintree,  in  Massachusetts.  (Hunt,  Chem.  and 
Geol.  Essays,  pages  4()o-407.) 

§  223.  In  1868,  an  examination  made  by  Mr.  Richardson, 
of  tlie  south  side  of  the  St.  Lawrence,  from  near  Quebec, 
for  a  distance  of  more  tha.i  150  miles,  as  far  as  Bic, 
showed  that  a  considei-able  part  of  the  strata  along  the 
shore,  at  first  called  Hudson  River  group,  andsu])sequently 
referred  to  the  Lauzon  division  of  the  Quebec  group,  con- 
tains organic  remains  of  Lower  Potsdam  age.  These  strata, 
consisting  of  quartzites  and  sandstones,  with  bedded  lime- 
stones and  shales,  have  a  thickness  of  about  2,000  feet. 
The  sandstones  and  quartzites  are  often  conglomerate,  con- 
taining pebbles  and  large  masses  of  limestone,  in  which  occur 
in  abundance  the  fossils  of  the  Lower  Potsdam,  l)ut  ^(dter- 
ella.  was  said  to  be  also  found  in  t  he  bedded  limestones,  ;ind 
ArcJieocyatJiVS  in  the  shales.  The  chief  localities  of  tliese 
fossils  were  at  St.  Denis  and  Bic  Harbor.  These  strata 
were  supposed  to  be  unconformably  overlaid  by  tlie 
Quebec  group  ;  but  in  a  region,  the  stratificati(m  of  which,  as 
we  have  already  seen,  (^  177)  is  so  greatly  disturbed,  faulted, 
and  even  invei'ted,  much  more  study  is  required  before  the 
true  structui-e  of  the  region,  and  the  real  age  of  these  con- 
glomerate beds  can  be  satisfactorily  determined.  (Report 
for  1808,  pages  120-180.) 

§  224.  Without  counting  the  Lower  and  the  TliiperCalci- 
ferous  of  Newfoundland,  we  liave  seen  that  the  great  con- 
tinental belt  of  rocks,  originally  designated  the  Hudson 
River  group,  and  subsequently  called  Upper  Taconic  and 
Quebec  grouji,  has  already  afforded  us  at  least  three  dis- 
tinct faunas :  1°,  that  of  the  Red  sandrock,  or  ro-called 
Lower  Potsdam  ;  2°,  that  of  the  Levis  limestone ;  and  3°, 
that  of  the  Phyllograptus  sliales  of  Quebec,  whicli  liave 


RELATIONS  OF  THE  SILLERY    FORMATION.         E,    IVi 


Ici- 
[on- 
Ison 
inid 
his- 
lled 

13°, 

tive 


also  been  met  with  in  more  than  one  locality  in  Newfound- 
land. Still  another  fauna,  included  in  the  Quebec  group, 
will  be  described  in  §  233.  Tn  the  language  of  Billings, 
"the  Quebec  group,  in  fact,  consists  of  several  formations, 
differing  from  each  other  lithologically  and  palt'ontologi- 
cally,  and  yet  forming  a  connected  series."  (Paleozoic  Fos- 
sils, Vol.  I,  page  02.) 

§  225.  A  grave  question  here  arises,  as  to  the  relation 
to  the  other  members  of  the  Quebec  group,  of  the  SiHery 
formation.  This,  when  those  were  supposed  to  belong  to  the 
summit  of  the  (vhamplain  division,  was  referred  to  the  over- 
lying Oneida  formation,  and  wlien  they  were,  on  paleonto- 
logical  grounds,  assigned  a  position  near  the  base  of  that 
division,  was  provisionally  regarded  as  a  superior  member 
of  the  Quebec  grou]).  In  an  early  chapter  of  the  Geo/or/// 
of  Canada,  Logan,  while  inclining  to  this  view,  declared 
that  "in  describing  the  Quebec  grouj)  the  series  will  be 
considered  as  an  ascending  one.  not  so  much,  howevci,  for 
the  purpose  of  asserting  the  ordei'of  the  sti-ata,  as  to  render 
more  intelligible  the  facts  connected  with  their  geographical 
distribution."  (Page  229).  Billings,  about  the  same  time, 
noticing  the  Oholella^  which  was  found  in  shales  "  intei-- 
stratilied  with  the  Sillery  sandstones,  which  are  at  present 
classilied  as  the  upper  part  of  the  Quebec  group,"  adds, 
"but  the  question  as  to  whether  such  is  their  true  ])osition  or 
not,  is  considered  an  open  one."  (Pal.  Fossils  1,  i)agr(;'.)). 
The  Sillery  sandstones,  as  seen  at  Granby  (^  178,)  wci'c 
plainly  overturned,  in  an  inverted  synclinal  or  anticlinal ; 
and  their  attitude  in  the  vicinity  of  Quebec,  and  elsewhere 
along  the  south  shore, where  inversion  seems  to  be  th«'  iiilc 
rather  than  the  exception,  (§  177)  was  such  that,  as  we  have 
seen  above,  thcii-  real  position  in  the  series  was  by  Logan 
regarded  as  undetermined. 

§  226.  If  not  at  the  snniinit,  their  ])o.sition  must  Ix-  at  the 
base  of  the  great  series  of  strata  in  question.  Tliey  were, 
however,  very  unlike  the  basal  sandstones  seen  on  the  north 
side  of  the  strait  of  Bdlisle,  and  were  met  with  in  New- 
foundland only  in  two  localities  in  the  noi'th-west  poition  of 
the  island,  at  Bonne  Bay,  and  at  Pistolet  Bay.     It  will  bo 

[8  E.  1 


I    it 


B 


1 1 


> 


III! 


114   E.       SPECIAL    REPORT.       T.  STERRY   HUNT,   187i), 

recollected  that  the  crystalline  rocks  of  the  Notre  Dame 
range  had  been  by  Logan  asserted,  in  accordance  with  the 
hypothesis  of  Mather,  to  be  formed  by  a  metamorphosis  of 
the  strata  of  the  Quebec  gronp,  and  a  horizon  of  serpentinic, 
hornblendic,  and  chloritic  rocks,  wa.s  supposed  by  him  to 
occur  at  the  summit  of  the  Lauzon  fonnation.  At  Bonne 
Bay,  as  described,  the  uncrystalline  fossiliferous  limestones 
and  shales  were  seen  to  dip  south-east,  at  a  higii  angle, 
apparently  beneath  a  conformable  mass  of  the  Sillery  sand- 
stones ;  while  a  little  distance  across  the  strike  crystalline 
rocks,  like  those  of  Notre  Dame  range,  rise  in  a  mountain- 
mass. 

§  227.  At  Pistol et  Bay  the  fossiliferous  strata  are  also  seen 
dipping  to  the  south-east  at  a  high  angle  towards  a  belt  of 
similar  crystalline  rocks  on  the  opposite  side  of  the  bay. 
Here,  the  Sillery  sandstone  is  not  seen  in  the  interval,  but 
appears  on  the  south-east  side  of  the  belt  of  serpentinic, 
.?blovitic,  and  hornblendic  rocks.  Upon  this  relation  of 
things,  Logan  remarks  that  the  crystalline  rocks  here  oc- 
cupy their  supposed  position,  towards  the  summit  of  the 
Quebec  group,  while  the  massive  greenish  chloritic  sand- 
stones succeeding  them  "would  thus  appear  to  occupy  the 
horizon  which  has  been  j^rovisionally  assigned  to  those  of 
the  Sillery  formation,  near  Quebec,"  adding  that  "further 
research,  however,  is  yet  required  to  establish«the  true  re- 
lation of  this  formation  to  the  Quebec  group."  (Geol.  Can- 
ada, page  880.) 

§  228.  The  ])i'esent  writer  has,  for  many  years,  believed 
that  the  position  of  the  Sillery  sandstones  is  at  the  base, 
instead  of  at  the  summit  of  the  Quebec  group,  and  that  the 
whole  series  is  more  recent  than  the  crystalline  rocks  of  the 
Atlantic  belt,  to  which  the  Notre  Dame  and  Shickshock 
^[ountains,  and  the  similar  crystalline  rocks  in  Newfound- 
land (^  218)  belong.  The  order  at  Quebec,  according  to  this 
view,  is  a  reversed  one,  due  to  an  invei  i.ed  fold,  while  the 
dl[)i)iiig  of  the  uncrystalline  strata  southwards  towards  the 
ciystalline  rocks,  and  apparently  beneath  them  at  Bonne 
Bay  and  PistoletBay,  is  connected  with  the  numerous  faults 
whicli,  with  up-throwson  the  south-east  side,  liave  been  no- 


RELATIONS   OF  THE  SILLEKY  FORMATION.        E.    115 


lase, 
the 
the 
lock 
jiui- 
Ithis 
the 
the 
Inne 
lilts 
no- 


ticed at  the  latter  locality  (§  219.)  These  phenomena,  alike 
at  Quebec  and  in  Newfoundland,  are  in  close  accordance  with 
those  seen  everywhere  along  the  north-western  base  of  the 
Atlantic  belt,  from  Virginia  to  Gaspd,  as  so  abundantly 
established  by  the  concurrent  testimony  of  the  Messrs.  Ro- 
gers, Mather,  Logan,  and  Emmons,  already  set  forth.  (§  16, 
72,  75,  109,  110,  177-179.) 

§  229.  The  normal  position  of  the  Sillery  is,  according  to 
this  view,  seen  to  the  south-east  of  Pistolet  Bay,  where  the 
Sillery  sandstones  succeed  to  the  crystalline  rocks.  Sedi- 
mentary beds  of  this  kind  take  their  character  from  the  ad- 
jacent crystalline  formations,  and  as  the  serpentinic,  horn- 
blendic,  and  chloritic  rocks  furnish,  by  their  disintegration 
and  decay,  very  different  materials  from  the  Laurentian 
gneisses  of  the  Labrador  coast,  we  fine  ;:he  Sillery  sand- 
stones and  shales  unlike  the  basal  beds  of  that  region,  or  of 
New  York,  and  central  Canada.  It  will  be  recollected  that 
Emmons,  in  describing  the  Upper  Taconic  (Quebec)  series, 
asserts  that  its  basal  beds  are  greenish  chloritic  sandstoi.es 
and  conglomerates,  formed  from  the  ruins  of  the  crystalline 
rocks,  and  sometimes  seen  to  rest  directly  upon  them. 
(§  107.)  As  the  results  of  repeated  dislocations,  with  up- 
throws in  the  eastern  side,  however,  the  whole  order  is  gen- 
erally, according  to  him,  apparently  inverted  ;  the  black 
fossiliferous  shales  of  the  summit  appearing  to  dip  eastward 
beneath  all  the  other  members,  and  the  greenish  sandstones 
seemingly  overlying  the  whole,  as  seen  in  the  Granville  sec- 
tion.    (§\o7-ll().) 

§  230.  The  present  \vTiter  urged,  in  1872,  that  the  Levis 
limestones,  which  apx)arently  correspond  to  the  Tremadoc 
rocks  of  Great  Britain,  occupy  in  the  Quebec  section  a  po- 
sition nearer  to  the  Sillery  than  does  the  graptolitic  zone, 
which  is  clearly  the  equivalent  of  the  less  ancient  Arenig  or 
Skiddaw  rocks ;  from  which  follows  the  stratigraphical  in- 
version of  the  whole  series.  (Ohem.  and  (UhA.  Essays,  pages 
412-41:5.)  Tills  view  was  shared  by  Mr.  Billings,  who,  in  a 
private  communication,  in  January,  1870,  shortly  bel'on?  his 
death,  informed  the  writer  that  the  Obolella  preihsa  of  the 
Sillery  is  apparently   identical  with  0.  maculala.  Hicks, 


110   E.      SPJX'IAL   REPORT.      T.  STERRY  HUNT,  1875. 


i'M 


from  the  Meneviiin  of  Wales.  He  had  also  recoy,iiized 
(JftliU  HicksU,  Salter,  a  Menevian  species,  in  the  Lauzon, 
or  so-called  Lower  Potsdam  beds  of  Bic  Harbor.  (§  223.) 

§  231 .  The  north-western  lindt  of  the  strata  of  the  Quebec 
uroiip,  in  Canada,  is  nearly  defined  by  a  line  running  from 
(Jape  Rouge,  in  the  vicinity  of  Quebec,  to  the  northern  ex- 
trendty  of  Missisquoi  Bay,  on  Lake  Champlain.  The  rocks 
to  the  south-east  of  this  line,  including  alike  the  fossiliier- 
ous  strata,  and  the  ci-ystalline  rocks  of  the  Notre  Dame 
range,  supposed  to  })e  the  same  strata  in  an  altered  condi- 
tion, were  described  by  Logan  as  l)eing  Jirranged  "in  long, 
narrow,  parallel,  synclinal  and  anticlinal  forms,  with  many 
overturn-dips.  The  latter  circumstance  makes  it  diliicult 
to  determine  which  of  these  folds  are  synclinal,  and  which 
anticlinal,  inasmuch  as  the  outcrops  in  both  cases  present  a 
sinnlar  arrangement.  Tlie  weight  of  evidence,  however, 
goes  to  show  that  the  strata  dij)  to  the  centers  of  the  areas 
about  to  be  described,  and  they  will,  therefore,  be  designa- 
ted as  synclinals."  They  were  declared,  in  the  region  in 
question,  to  be  three  in  number,  of  which  the  first,  or 
north-western  one,  included  the  uncrystalline  strata  al- 
ready described  in  some  detail,  as  seen  near  Quebec,  at  St. 
Flavien,  on  the  St.  Francis,  at  Acton,  Ui)ton,  and  Wick- 
ham,  at  Granby,  Farnham,  Bedford,  and  Phillipsburg. 
(Geology  of  Canada,  pages  234  and  790,  and  Report  for 
1863-6(5,  pages  29-39.) 

§  232.  The  evidence  above  alluded  to  was  that  deduced 
from  the  section  near  Que})ec,  according  to  which  it  was 
supposed  that  the  Sillery  sandstones  were  the  highest 
rocks,  and  appeared  only  in  the  deeper  parts  of  the  first 
synclinal,  wliich  was  partially  divided  by  subordinate  anti- 
clinids  into  lesser  basins.  Certain  carbonaceous  slates,  with 
thin  beds  of  sandstone  and  impure  limestone,  which  appear 
upon  the  supposed  anticlinals,  were,  by  Logan,  conceived 
to  be  older  than  the  Quebec;  group,  and  referred  by  liim  to 
the  Potsdam.  These,  however,  were  found  at  Farnham  to 
contain  many  organic  remains,  among  which,  according  to 
Billings,  are  trilobites  belonging  to  the  genera  Ampyx, 
Dalmanifes,  Liclias,  Trlarthrus,  and  Agnostiis,  together 


BLACK    SLATES    OF    FARNHAM. 


E.    117 


with  undescribed  giuptolites,  a  Leptaena  like  L.  sericea, 
and  a  Plllodlctf/a  like  P.  acuki.  These  forms,  it  was  said, 
are  not  what  "might  be  expected  in  the  Potsdam  forma- 
tion, so  tliat  the  Farnham  slates,  with  similar  ones  in  other 
localities,  may  be  brought  into  position  by  some  of  the 
many  complicated  dislocations  which  affect  the  strata. 
Except,  however,  where  such  fossiliferous  strata  are  knf)wn 
to  occur,  (he  black  slates  and  limestones  will  be  provision- 
ally described  as  older  than  the  Quebec  group."  (Geology 
of  Canada,  pages  2;U,  236,  239,  240.)  Subsequently,  how- 
ever, Logan  declared  with  regard  to  these  black  slates  and 
limestones,  supposed  to  be  related  to  the  Potsdam  group, 
that  it  " appears  to  be  difficult  to  separate  them  from  the 
Phillipsburg  rocks,  and  these  being  paleontologically  con- 
nected with  the  lower  1,285  feet  of  the  Levis  series,  the 
whole  naturally  constitutes  one  group."  The  original 
Levis  formation  was  now  first  divided,  and  it  was  said  that 
the  "lower  or  Levis  division  comprehends  the  Phillipsburg 
series,  the  black  shale  above  it,  autl  the  lower  1,285  feet  of 
the  Orleans  section."  The  remainder  of  this  last  was 
called  Lauzon.  (§  203.)  (Report  for  1853-66,  pages  30-31.) 
The  pages  here  quoted,  though  bearing  the  name  of  Mr. 
James  Richardson,  were  written  by  Sir  W.  E.  Logan. 

§  233.  The  black  slates  or  shales,  now  included  in  the  Levis 
formation  of  the  Quebec  gronj),  (and  placed  higher  than 
the  Phillipsburg  limestone,)  were  thus  the  same  whicli, 
from  their  relations  to  the  folded  stratii  in  the  supposed 
north-western  synclinal,  were  at  one  time  conceived  to  un- 
derlie the  whole  Levis  or  Orleans  section,  and  were  still 
placed  at  or  near  its  base.  From  their  fossils,  however, 
these  slates  belong  to  a  liorizon  above  that  assigned  to  the 
Quebec  group,  and  corresi)ondiiig  to  the  Trenton,  or  the 
still  higher  members  of  tlie(Jhaniplain  division.  Wc  have 
tlius  a  fourth  fauna  included  in  the  Levis  formation,  (;^  224.) 
If,  however,  as  we  have  endeavored  to  show,  the  position 
of  these  black  shales  is  really  at  the  summit  and  not  at  the 
base  of  the  so-called  Quebec  group,  whicli  is  an  inverted 
series,  the  anomaly  disappears,  and  we  have,  in  ascending 
order: — 1°,  the  Sillery  sandstones  ;  2°,  the  trilolutic  beds  of 


5  ii 


:t. 


i  j 


118  E,      SPECIAL   REPORT.      T.  STERRY  HUNT,  1875. 

Levis  and  Phillipsburg  ;  3°,  the  Pbyllograptiis  shales  of 
Quebec  ;  and  4°,  the  black  shales  of  Farnham  ; — in  whicli  the 
succession  is  in  accordance  with  the  well  known  facts  of 
paleontology. 

§  234.  We  may  here  notice  the  judgment  of  Prof.  James 
Hall  at  this  stage  of  the  inquiry.  He  had  hitherto  em- 
ployed the  name  of  the  Hudson  Iliver  group  as  synonymous 
with  the  Loraine  shales  ;  but  in  18G2,  in  a  note  to  his  Ge- 
ology  of  Wisconsin,  page  443,  he  referred  to  the  evidence  of 
organic  remains  recently  found  in  the  Hudson  Iliver  slates 
in  Vermont  and  Canada,  "which  prove  conclusively  that 
these  slates  are,  to  a  great  extent,  of  older  date  than  the 
Trenton  limestone,"  although  probably  posterior  to  the 
Potsdam.  He  remarked,  moreover,  that  "  the  occurrence  of 
well  known  forms  of  the  second  fauna — LeptcBna  serlcea, 
Orthls  tesiudinarla,  Asaplms  {Isoielus\  Tri nucleus,  etc. — 
in  intimate  relation  with,  and  in  beds  apparently  consti- 
tuting a  part  of,  the  series  along  the  Hudson  liiver  requires 
some  explanation.  Looking  critically  at  the  localities  in 
the  Hudson  valley  which  yield  these  fossils  we  find  them 
of  limited  and  almost  insignificant  extent.  Some  oi"  them 
are  at  the  summits  of  elevations  which  are  synclinal  axes, 

*  *  where  the  remains  of  newer  formations  would 
naturally  occur.  Others  are  apparently  unconformable  to 
the  rocks  below,  or  are  entangled  in  folds  of  the  strata, 

*  *  while  the  enormous  thickness  of  beds  exposed  is 
almost  destitute  of  fossils."  The  graptolites  of  the  Hudson 
valley,  "which  have  hitherto  been  referred  to  the  age  of  the 
other  fossils  found  in  the  small  outliers,  or  to  the  second 
fauna,  in  reality  hold  a  lower  position,  and  belong  to  the 
great  mass  of  slates  below," 

He  concluded  that,  inasmuch  as  the  Hudson  River  rocks, 
in  their  typical  localities,  are,  as  a  body,  older  than  the 
Trenton  limestone,  which  is  itself  older  than  the  Loraine 
shales,  and  the  shales  and  sandstones  of  Pulaski,  "the 
term  Hudson  River  group  cannot  properly  be  extended  to 
these  rocks,  Avliich,  on  the  west  side  of  the  Hudson,  are 
separated  from  the  Hudson  River  group  proper  by  a  fault 


WING   ON    THE   GEOLOGY    OF    VEHMONT. 


E.    119 


lat 


3ks, 
the 
line 
the 
to 
are 
I  lilt 


not  yet  fully  ascertained."     See  further  §  237  and  for  the 
Pulaski  rocks  the  note  to  §  249. 

§  235.  There  are  not  wanting  evidences  elsewliere  that  the 
fauna  of  the  upper  half  of  the  Cham  plain  division  is  in- 
cluded in  this  disturbed  belt.  The  obstM-vations  of  the 
Rev.  Augustus  Wing,  and  those  of  Mr.  Billings,  in  Ver- 
mont, which  are  to  the  point,  were  described  by  tlie  present 
v^Titer  in  a  communication  on  the  Geology  of  Vermont, 
read  before  the  American  Association  for  the  Advancement 
of  Science,  at  Chicago,  in  1868.  In  a  section  from  Crown 
Point,  in  New  York,  eastward  across  Lake  Clia.mplnin  to 
Bridport,  in  Vermont,  the  western  part  exhibits  the  whole 
succession  of  the  Champlain  division,  from  the  Potsdam 
sandstone  to  the  Loraine  shales,  which  are  overlapped  by  the 
Red  sandrock,  as  already  described  (§  116).  This,  dii)ping 
to  the  east,  is  overlaid  by  a  great  mass  of  limestones,  seen 
in  Sudbury,  which  yielded  to  Wing  and  to  Billings  the 
fauna  of  the  Calciferous  sand-rock,  with  other  forms  like 
those  of  the  Levis  limestone.  Next  in  ascending  sequence, 
also  in  Sudbury,  was  found  a  mass,  estimated  at  not  less 
than  2,000  feet,  of  limestones  holding,  in  abundance,  the 
fauna  of  the  Trenton,  and  probably  including  tliat  of  the 
Cha7y\  To  the  east  of  this,  again,  a  fault,  marked  by  a 
ravine,  brings  up  against  the  Ti-enton  the  Levis  limestone, 
from  which  Mr.  Billin,u:s  obtained  numerous  characteristic 
fossils,  including  Balhiiunis  ^affordl.  Tliese  fossils  abound 
in  Sudbury,  Cornwall,  Middlebury,  and  Brookville,  where, 
according  to  him,  they  are  closely  associated  with  the  white 
marbles  quarried  in  this  region.  (Amer.  Jour.  Science  [2], 
XLVI,  227.)  This  succession  recalls  the  section  in  New- 
foundland (§  220)  with  foi'ms  apparently  of  Trenton  age,  and 
raises  the  question  whether  a  careful  study  of  the  latter 
locality  might  not  show  the  presence  of  the  higher  members 
of  the  Champlain  division. 

§  236.  The  strata  in  this  section  examined  by  Wing  and 
Billings,  appear  in  their  normal  order,  and,  though  alfected 
by  undulations,  and  by  great  up-throwson  the  eastern  side, 
are  not  inverted.  Further  northward,  however,  Logan 
found  remarkable  examples  of  inversion,  one  of  which  is 


■  s  '■  ■ 


r^f 


120   E.       SPKCIAL    liKPOUT,       T.   STERRY    HUNT,  1875. 


ill 


seen  near  Hi<;h<^ate  Springs,  where  the  Trenton  limestone, 
on  the  west  side  of  an  anticlinal,  becomes  vertical,  and  in 
places  assumes  an  eastward  dip.  About  eight  miles  further 
south,  at  Smith's  lime- works,  the  Trenton  limestone  is  over- 
tuiued  and  overlaid  in  successicm  by  the  Black  River  lime- 
stone and  by  a  series  of  sandstones  and  dolomites  regiirded 
as  belonging  to  the  Chazy.  The  whole  of  this  inverted  series, 
measuring  about  000  feet,  lias  an  eastward  dip,  ranging  from 
45°  to  75°  beyond  the  jjerpendicular.  Within  a  distance  of 
150  yards  to  the  east,  according  to  I^ogan,  appears  the  Red 
sand-rock,  with  a  gentle  dip  to  the  east.  It  here  consists  of 
red  and  white  sandy  dolonntes,  int<'rstratilied  with  dark- 
colored  shales,  in  both  of  which  are  found  the  charactei'istic 
fossils  of  the  Lower  Potsdam,  tin.'  whole  series  having  a 
thickness  of  2,200  feet.  For  an  account  of  these  inverted 
sections,  see  Geology  of  Canada,  joages  275-280,  and  also 
page  855,  where  designs  of  them,  drawn  to  a  scale,  are  given. 
§  237.  In  1868,  Logan,  in  company  with  Professor  James 
Hall,  exanuned  the  i-ocks  of  eastern  New  York  which  had 
been  designated  bv  Eaton  as  Argilliteand  Transition  (Iray- 
wacke,  (§61  ;)  by  Mather  as  belonging  to  the  Hudson  River 
group  (Loraine,)  and  the  Oneida  and  Medina  formations, 
(§  75-77 ;)  by  Emmons,  first  assigned  to  the  same  horizon, 
(§  94,)  and  subsequently  regarded  as  a  great  and  peculiar  de- 
velopment of  strata  of  the  age  of  the  Calciferous  sand-rock, 
(§  96,)  which  he  afterwards  called,  successively,  the  Taconic 
slates,  (§  10:3,)  and  the  Upper  Taconic  series,  (§  107-108.) 
These  rocks,  described  by  Logan  as  consisting  of  greenish 
sandstones  and  conglomerates,  with  shales,  sometimes  red 
and  green,  and  with  slialy  and  concretionary  limestones, 
including  the  Sparry  lime-rock  of  Eaton,  were  declared  to 
belong  to  the  Quebec  group.  They  were  described  as  occu- 
pying nearly  the  whole  of  Rensselaer,  Columbia,  and  Dutch- 
ess counties  ;  the  Sillery  formation  being  largely  developed 
in  the  first-named  county,  but  scarcely  extending  south  of 
it.  To  the  westwtird,  in  approaching  the  river  Hudson,  these 
rocks  were  replaced  by  the  lithologically  distinct  and  more 
recent  strata  of  the  Loraine  formation,  a  narrow  belt  of  whiidi 
was  traced  along  the  east  side  of  the  river  to  a  point  a  little 


LOGAN    ON   THE   QUEBEC   (iUoUP. 


E.    121 


le- 


u- 
h- 


Ire 
le 


above  Hyde  Park,  where  the  houiuhiry  between  the  two  for- 
mations crosses  to  the  west  bank,  and  the  slates  and  lime- 
stones of  the  Quebec  j^roiip  thence  occupy  both  sides  of  the 
river  down  to  the  Highlands,  which  were  declared  to  be  of 
Lainvntian  age.  The  results  of  these  investigations  are 
stat«'d  in  a  note  prei)ared  l)y  the  present  writer,  with  the 
approval  of  Sir  William  Logan,  and  published  in  the  Cana- 
dian NatiLTalist,  in  1804,  (vol,  I,  page  809.)  They  are  also 
embodied  in  the  geological  map  of  Canada.  (,^  44.) 

§  288.  What  were  the  relations  between  the  older  rocks, 
whether  called  Lower  Potsdam  or  Quebec  gi'oup,  and  the 
higher  members  of  the  (Jhamplain  division  found  along  their 
western  border;  We  have  seen  that  Logan  had  foruicrlv 
supposed,  with  Mather,  that  this  line  marked  a  great  anti- 
clinal axis  (§  195.)  The  later  view  of  the  Quebec  group, 
arrived  at  by  Logan,  in  1801,  made  this  hypothesis  no  longer 
tenable,  and  a  new  one  was  put  forward  by  him  in  1801, 
in  the  Canadian  Naturalist,  (vol,  VI,  page  199,  which  is  set 
forth  in  the  G-eologv  of  Canada,  (pages  294-297.)  The  new 
hypothesis  supposed  that  tlie  whole  series  of  rocks,  includ- 
ing the  Potsdam  and  Quebec  groups,  and  the  succeeding 
Trenton,  Utica,  and  Loraine  formations,  had  been  laid  down 
confornia])ly,  and  without  disturbance.  Logan  conceived 
that  the  deposition  had  taken  place  along  the  south-east 
border  of  a  Ljiurentian  continent,  and  that  \\  liile  the  great 
accumulations  of  the  Potsdam  and  Quebec  groups  were 
going  on,  the  typical  Potsdam  sandstone  and  the  Cal- 
ciferous  sand-rock  of  the  New  York  series  were  laid  down 
over  an  adjacent  terrace  or  shallow  basin,  which  was  sub- 
merged at  intervals.  It  was  not  until  the  close  of  the  Cham- 
plain  period,  that  a  great  break,  with  an  uplift  of  7,000  feet, 
was  imagined  to  have  lu'ought  up  the  lower  strata  on  the 
south-east  side  of  th«^  dislocation,  causing  them  to  over  ride 
the  broken  edges  of  the  higher  formations.  This  supposed 
line  of  break  and  upthrow  of  7,000  feet,  was  coincident 
with  the  former  anticlinal  axis  of  Mather  and  Logan  (§  09- 
71,  195),  and  was  now  said  to  extend  from  Gasp^  to  Ala- 
bama. 

§  239.  Such  a  dislocation,  so  near  the  continental  border, 


.  Jr  ■ 


t« 


122   E.      SPECIAL   REPORT.      T.  STERRY    IIITNT,  1875. 


it  was  sought  to  explain  by  assuming  for  the  shore  of  the 
ancient  continent,  a  gi'eat  heiglit  and  a  very  steep  inclina- 
tion. In  the  word.s  of  Logan:  "During  the  Potsdam 
period,  in  the  neighborhood  of  Quebec,  we  see  that  the  sur- 
face of  the  quartzo.se  gneiss  now  supporting  the  Trenton 
limestone  at  the  Falls  of  Montmorenci,  must  have  been 
7,000  feet  above  the  gneiss  under  the  Island  of  Orleans, 
while  the  distance  between  the  two  posi^^'-^ns  does  not 
much  exceed  a  mile  and  a  half.  This  wo  jive  a  slope 
of  nearly  45°,  and  perhaps  it  would  not  be  oxlravagant  to 
take  this  as  representing  the  inclination  along  the  whole 
line  to  Alabama.  As  the  Potsdam  and  Quebec  groups  ac- 
cumulated, their  edges  would  abut  against  this  slope,  and 
ultimately  both  these  and  the  early  shallow- water  deposits 
on  the  higher  terrace  (the  typical  Potsdam  sandstone  and 
Calciferous  sand-rock)  would  be  covered  over"  by  the  Tren- 
ton limestones  and  Mie  Utica  and  Loraine  formations. 
This  supposed  condition  of  things  was  illustrated  by  an 
ideal  diagram  (page  296),  in  which  the  whole  succession, 
including  the  black  shales  of  the  Potsdam  at  the  base,  are 
represented  as  horizontal  strata,  the  Potsdam  dng  overlaid 
by  the  Quebec  group,  which,  in  its  turn,  if  ^red  by  the 
Trenton  and  the  higher  formations.  On  pagv,  234  another 
diagram  represents  these  deposits  after  the  supposed  break, 
in  a  section  from  Montmorenci  to  Orleans  Island. 

§  240.  This  explanation  requires,  according  to  the  admis- 
sion of  Logan,  the  extraordinary  condition  of  a  mountain- 
range  stretching  from  Gasp^  to  Alabama,  rising  from  the 
sea  with  "a  slope  of  nearly  forty-live  degrees  "  to  a  height 
of  7,000  feet,  which  gradually  subsided,  as  accumulation 
went  on  along  its  base,  until  it  was  completely  submerged. 
The  facts  of  the  case,  however,  do  not  require  any  such 
geographical  improbability  to  account  for  them,  and  a 
simpler  explanation  of  the  problem  is  found  in  the  exist- 
ence of  an  unconformity  between  the  Trenton  limestone 
and  the  older  members  of  the  paleozoic  series. 

§  241.  Movements  of  the  earth's  crust,  resulting  in  folded 
and  inverted  strata,  have  demonstrably  taken  place  along 
the  Atlantic  belt  at  several  periods.     The  Silurian  lime- 


NON-CONFORMITIES  IN  THE  ATLANTIC  HKLT.     E,  123 


il 


Stones,  (including  those  of  Niagara  and  Lower  Ilelderberg 
age,  which  constitute  the  Gasp^  limestones  of  north-eastern 
Canada  (^  175),)  are  found  near  Montreal,  resting  transgress- 
ively  ui)C)n  the  erod*  d  edges  of  the  Cliamplain  division,  and 
further  east  in  like  manner,  both  upon  the  strata  of  the  Que- 
bec group  and  upon  the  crystalline  rocks  of  the  Notre  Dame 
range.  Throughout  the  Atlantic  belt,  in  Canada,  these 
Gaspd  limestones  are  folded,  faulted,  often  at  high  angles,  f 
and  sometimes  vertical  and  even  inverted,  (Geol.  of  Can- 
ada, page  429.)  In  Gaspd,  where  they  are  conformably 
overlaid  by  the  Devonian  sandstones,  fragments  of  both  of 
these  enter  into  the  conglomtvate  of  the  Lower  Carl )onifer- 
ous,  which  rests  upon  them  unconformably.  This,  in  its 
turn,  is  more  or  less  disturbed,  and,  in  parts  of  New 
Brunswick,  its  strata  appear  nearly  or  quite  vertical  in  at- 
titude. There  is,  in  this  region,  a  want  of  conformity  be- 
tween the  Lower  Carboniferous  and  the  Coal  measures, 
which  are,  themselves,  often  much  disturbed,  and  l)ear  upon 
their  upturned  edges  beds  of  Triassic  sandstone,  which, 
itself,  is  sometimes  raised  to  an  angle  of  45°.  We  have 
thus  along  the  Atlantic  belt,  in  the  provinces  of  Quebec 
and  New  i'runswick,  evidences  of  at  least  five  periods  of 
movement,  arked  by  parallel  foldings  of  the  strata  and  by 
unconformity,  subsequent  to  the  deposition  of  the  rocks  of 
the  Champlain  division,  namely  :  1,  post-Siluro-Cambrian ; 
2,  post-Devonian  ;  3,  post-Lower  Carl)oniferous  ;  4,  post- 
Carboniferous  ;  5,  p<jst-Triassic. 

§  242.  Analogy  would  lead  us  to  suppose  that  similar 
movements,  givin^jj  rise  to  unconformity,  might  have  oc- 
curred during  the  Cambrian  period.  Logan  himself,  after 
having  maintained  the  contrary,  conjectured  a  discordance 
between  the  Potsdam  and  the  Quebec  group  in  V^ermont, 
(Amcr.  Jour.  Science  [2],  XLVI,  225,)  and  subsequent  re- 
searches, in  1808,  on  the  south  shore  of  the  St.  Lawrence, 
below  Quebec,  led  him  to  admit  such  an  unconformability 
in  that  region.  (§  223.)  The  evidence  of  a  want  of  con- 
formity between  the  Birdseye  and  Black  River  limestones, 
(the  basal  portion  of  the  Trenton)  and  the  inferior  members 
of  the  Champlain  division,  is  in  great  part  indirect,  but  is 


:[.■ 


124   E.       SPKCIAL    REPORT.       T.  STERRY  HUNT,   1875. 


M- 


Illt# 


* 


jii 


cumulative.  There  exists,  in  the  first  place,  a  complete 
paleontological  break  at  this  horizon.  According  to  the 
carel'ul  determinations  of  Mr.  Billings  up  to  1872,  when 
they  were  furnished  by  him  to  the  present  writer,  we  lind 
in  the  Chazy  limestone  of  the  Ottawa  basin  ninety  species 
of  organic  remains,  of  which  twenty-two  are  known  to  pass 
ui)wards  into  the  directly  overlying  Birdseye  and  Black- 
River  limestones  ;  while  of  the  forty-four  species  found  in 
the  Calciferous  of  that  region  but  two  are  met  with  in  the 
Cluizy.  This  latter  break  is  elsewhere  filled  by  the  Levis 
(and  Phillipsburg)  limestones,  containing  twelve  species 
from  the  CuU'iferous  and  five  from  the  Chazy  ;  but  of  the 
whole  fauna  of  the  Levis  limestones,  and  the  Quebec  Pliyl- 
lograptus  shales,  amounting  in  all  to  more  than  200  species, 
not  a  single  one,  according  to  Mr.  Billings,  has  been  met 
with  in  the  basal  beds  of  the  Trenton  limestone  group. 
(Hunt.  Chem.  and  Geol.  Essays,  page  412.) 

§  243.  The  interposed  Chazy  limestone,  which  thus  forms 
a  connecting  link  between  the  Cahriferous  and  the  Trenton, 
bears  evidence  of  a  i)eriod  of  disturbance.  As  described 
by  Logan,  at  (Trenville  in  the  Ottawa  basin,  it  includes  a 
mass  of  fifty  feet  of  shales  and  sandstones,  while  its  base 
is  a  conglomerate  of  limestone  pebbles,  resting  on  a  fossil- 
iferous  magnesia n  limestone,  regarded  as  the  Calciferous 
sand-roclv.  Moreover,  in  Herkimer  county,  in  the  Mohawk 
valley,  according  to  Prof.  James  Hall,  the  Cliazy  is  absent, 
and  the  ])asal  beds  of  the  Trenton  rest  directly  u]Km  the 
Calciferous  sand  rock.     (Ibid,  page  414.) 

§  244.  Beyond  the  limits  of  the  Ottawa  basin,  to  the  west 
as  far  as  Lake  Huron,  the  Trenton  limestone  is  f(uind  rest- 
ing on  the  Primary  crystalline  ro^ks,  while  from  the  vicinity 
of  J^erthier,  about  fifty  miles  north-east  of  Montreal,  to 
Quebec,  and  l>eyond  to  Malbaie,  the  same  is  true.  Beds  of 
quartzose  conglomerate,  and  sandstones  sometiines  occur 
at  the  base  of  the  limestone  in  this  region,  but  where  these 
have  yielded  fossils,  as  at  Malbaie,  they  are  found  to  belong 
to  the  inferior  beds  of  the  Trenton.  Again,  at  Lake  St.  John, 
on  the  Sagiienay,  the  Trenton  is  found  to  rest  directly  on 
the  cfvstalline  rocks. 


' 


DEPOSITION  OF  THE  TRENTON  LIMESTONE!?.      E.    123 


ii 


le 
?st 


i.t' 

ur 

se 
ig 

11, 


§  245.  From  these  facts  it  is  plain  tliat  after  the  deposition 
of  the  Calciferous  and  Chazy  formations,  and  before  the 
time  of  tlie  Trenton,  there  was  a  considerable  contint  ntal 
movement,  by  which  the  deep  Trenton  sea  was  widely 
spread  over  regions  which  had  not  been  submerced  in  the 
earlier  part  of  the  Champlain  period,  and  deposited  its 
limestones  to  the  north  and  east,  far  beyond  the  limits  of 
the  immediately  preceding  formations.  (§  99.)  Still  further 
movements  took  place  over  parts  of  the  area  in  (piestion, 
as  is  shown  by  the  du-ect  supci-position  of  the  I'ticii  forma- 
tion npon  the  Primary  rocks  at  the  base  of  the  Adiron- 
dacks,  (§  101,)  and  tlie  discordant  superposition  of  the 
Utica  and  Loraine  u'pon  the  lower  members  of  the  Cham- 
plain  division  near  Ottawa.  (§  1(H).) 

§  240.  The  movements  which  resulted  in  the  oyerlapping 
by  the  Trenton  of  the  older  members  of  the  Champlain 
division,  do  not,  it  is  true,  necesaai'ily  imply  discordance, 
but  they  make  it  possible,  and,  when  taken  in  connection 
with  the  complete  paleontological  bivak,  highly  prol)aV)le. 
When  it  is  considered  that  the  alternative  of  denying  a 
want  of  stratigi'aphical  conformity  at  this  horizon  is  the 
acceptance  of  the  hypothesis  of  Logan,  (§  238,)  few.  we 
think,  will  hesitate  to  admit  that  tlie  period  immediately 
preceding  the  deposition  of  the  Trenton  must  have  be»'n 
marked,  along  the  Atlantic  belt,  by  a  niovt'nicnt  of  the 
earth's  crust,  which  resulted  in  the  uplifting,  faulting, 
folding,  and  frequent  inversion  of  that  great  mass  of  sedi- 
ments along  the  western  base  of  the  Primary  rocks,  which 
constitutes  the  Upper  Taconic  series.  The  Trenton,  Utica., 
and  Loraine  formations  would  then  be  laid  down  over  the 
disturbed  surface  of  these.  ]))'ecisely  as  over  the  still  older 
rocks  of  the  Laurentides.  in  this  connectiou  must  be  con- 
sidered the  statement  of  Emmons,  that  small  aieas  of  the 
last  two  named  formations  rest  un<'onformal)ly  upon  tlie 
laconic  rocks,  near  Chatham  in  eastern  New  York.    (§  !)7.) 

§  247.  These  newer  rocks,  including  the  Trenton  limestone 
group,  must  necessarily  have  shared  in  all  tlie  later  move- 
ments of  the  Atlantic  belt,  whicli,  as  we  have  sliown,  C(m- 
tinued  at  intervals  into  Mesozoic  time,  and  involved  even 


Mjl 


126   E.      SPECIAL   REPORT,      T.  STEURY  HUNT,  187o. 


lii 


lii 


1 1 1  'I  i 


Devonian  and  Carboniferous  strata.  The  similar  foldings 
and  inversions  of  the  upper  members  of  the  Champlain 
division  along  the  western  borders  of  the  Upper  Taconic 
series,  as  observed  by  Logan,  are  completely  analogous  to 
those  exhibited  by  the  Auroral  limestone  along  the  western 
base  of  the  Laurentian  of  the  South  Mountain,  in  Pennsyl- 
vania and  New  Jersey,  as  described  by  Rogers,  ( §  10  ; )  and 
the  facts  observed  by  Mather  in  eastern  New  York  (§  72)  are 
of  the  same  order.  The  phenomena,  in  many  cases,  show 
that  the  older  rocks  did  not  act  merely  as  passive  barriers 
in  these  movements,  but  themselves  yielded  to  the  lateral 
pressure,  so  that  they  over-ride  the  newer  strata,  which  j^ass 
beneath  them. 

§  248.  The  boundary  between  the  Upper  Taconic  or 
Quebec  group,  and  the  younger  members  of  the  Champlain, 
is,  in  this  view,  neither  an  anticlimil  axis,  as  taught  by 
Mather,  and  by  Logan,  previous  to  1801  ;  nor  ypt  a  line  of 
fracture  and  great  uplift,  as  subsequently  maintained  by 
the  latter ;  but  was  primarily  a  line  of  contact,  where  the 
Trenton,  and  the  succeeding  Utica  and  Loraine  formations, 
rest  unconformably  upon  the  disturbed  strata  of  tlie  Upper 
Taconic  series.  Tlie  relations  of  the  two  have  been  more  or 
less  complicated  and  obscured  by  subsequent  movements, 
involving  alike  the  younger  and  the  older  series,  as  above 
described,  and  giving  rise  to  many  minor  anticlinals,  inver- 
sions, and  uplifts,  which,  although  secondary  and  subsid- 
iary in  character,  seem,  at  first  sight,  to  afford  some  justifica- 
tion for  both  of  the  hypotheses  previously  proposed.  The 
view  that  the  relations  of  these  two  series  is  primarily  one 
of  stratigrapliical  discordance,  was  advanced  by  the  present 
writer  in  1871  and  1872.  (Chemical  and  Geological  Essays, 
pages  203,  413.) 


m^ 


^s, 


CHAPTER  IV. 

niSTOmCAL  SKETCH  CONTINUED. 

§  249.  Before  proceeding  to  a  further  discussion  of  the 
various  rock-fornuitions  found  beneath  the  horizon  of  the 
Trenton  limestone  group,  it  becomes  necessary  to  consider 
brieily  tlie  nature,  the  succession,  and  the  paleontological 
history  of  the  lower  paleozoic  rocks  in  Great  Britain  and  in 
continental  Europe,  and  to  compare  them  with  those  of 
North  America.  To  this  end,  a  tal)Ie,  prei)ared  with  the 
aid  of  one  published  by  Hicks,  in  1875,  is  subjoined,  in  which 
the  principal  divisions  of  these  roclcs  in  Great  I'iritain,  up 
to  tlie  summit  of  the  P)a]a  group,  (which  is  regarded  as  cor- 
responding witli  that  of  t  he  Loraine  shales,*)  are  enumerated 
in  ascending  order,  the  thickness  of  each  being  given.  (See, 
in  this  connection,  the  papers  of  Hicks,  Qiinr.  .lour.  Geo- 


*Tho  lioniiiio  slmlca  of  Emmons  conslituto  tlio  summit  of  tho  .Slluro-Ciim- 
biian  in  tlio  United  States.  Tliey  were  called  by  V'anuxem  tlio  ruIiiskiHlialos. 
and  made  l)y  him  tlu' npiicr  moinbor  of  tlic  Iludson-l^ivor  cronp,  wlnla  tho 
Franl'Cl'oit  s;ind.ston(!«  and  shales,  \vhit;li  In;  rctiaidcd  as  a  hiwor  miMnbor  of  tho 
siuno  group,  \vi'ro  by  him  oonloundoil  with  thu  Upper  Taoonio  rocks.  This 
question  will  bodiscus.sod  at  tho  end  of  tho  present  ehaptor. 


I 


f ! 


;r 


i 


I  • 


128  E.      SPECIAL   REPORT.      T.  STEKKY  HUNT,  1875. 

logical  Society,  vols,  xxix,  42,  and  xxxi,  192  ;  also  Hunt, 
Chemical  and  Geological  Essays,  pages  384-386.) 

LOWER  PALEOZOIC  KOCKS  IN  WALKS. 

Feet. 
VII.     Bala  group  or    Caradoc,  varying  in  thickness 

from  3.000  to 12,000 

VI.    Llandeilo  group,  often  much  exceeding    .   .   .    3,000 

Y.     Arenk.  grou|j,  divuletl  iuti-    Ujjpcr,  1,500   foot; 

Middle,  1,500  fcet,and  Lower,  1,000  feet.         he 

lovei'     division  of    the  Areuig   abouim  .    in 

graptolites,  and  is  e(|uivalent  to  the  Slciddaw 

slates.    It  corresponds  to  wliat  in  North  Wales 

ha.s  been  called  L'pjjer  Tremadoc,) 4,000 

IV.    Tremauoc  group, 1,000 

III.     Linoi/la-Flao  group,  including  Upper  or  Dol- 

gelly,  000  feet;  Middle  or  Festiniog,  2,000  feet; 

and  lower  or  Macntwrog,  2,500    feet.     (The 

lower  and   niiddh'  divLsions  of  the   LingulU 

Flags  are  equivah'ut,  rospoctively,  to  tlie  ilol- 

lybusli  sjuidstone  and    to  the  Olenus  slates  of 

Malvern,) 5,100 

II.    Menevian  grouj), tJOO 

1.     LoNOMVND    group,,    including    the     Llanberris 

shitcs  and  tlie  Harlecli  sandstones,  often  much 

exceeding 4,000 

§  250.  The  above  series  rei)resents  the  whole  of  the  Cam- 
brian of  Sedgwick,  as  defined  by  him  in  1838.  He  subse- 
quently divid(^(l  it  into  the  Lower  Cambrian  or  Bangor 
group,  ( i) ;  the  Middle  Cambrian  or  Festiniog,  ( ii,  iii, 
IV,)  and  the  Upper  Cambrian  or  Bahi  group,  (v,  vi,  vii,) 
vrhich  embraced  the  Bala,  Llandeilo,  and  Arenig  of  tiie 
present  sc^heme.  Wlien  lirst  named,  no  organic  remains 
were  known  in  Sedgwick's  first  and  second  groups,  and  the 
third  was,  by  an  ei'ror  of  IMurc^hison's,  claimed  as  a  lower 
nuMiibpr  of  his  Silurian  system,  (which  properly  includes 
the  succeeding  Llandovery,  Wenlock,  and  Ludlow  forma- 
tions.) He,  thei-eupon,  called  the  Upper  Cambrian  group 
of  Sedgwick,  Lower  Silurian,  a  name  which  was  adopted 
by  the  greater  number  of  geologists,  both  in  Great  Britain 
and  North  Ameiica.  The  name  of  Cambro-Silurian,  or 
better  that  of  Siluro-Cambrian,  has  been  by  many,  how- 
ever, used  to  designate  the  Upper  Cambrian  of  Sedg^^'ick, 
and  will  be  so  employed  in  the  following  pages. 


UPPER  AND  LOWER  CAMBRIAN   IX  WALPIS.        E.    129 


111, 

the 
hius 
the 
wer 
lies 
ma- 


tain 
or 

low- 
ick, 


§  251.  Miirchison  assumed  that  the  Siliiii:in,  as  thus  ex- 
tended downward  by  liim,  re})resented  tlie  dawn  of  life, 
and,  when,  at  a  later  date,  oi-fjanic  remains,  b(»l()n,iiin,£:  to  the 
so-called  Primordial  zone  of  ]3arrande,  were  found  in  lower 
portions  of  the  Cambrian,  attempted  to  annex  these  por- 
tions to  his  Silurian  system  under  the  name  of  Primordial 
Silurian  ;  restricting  the  name  of  Cambrian  to  the  Long- 
niynd  group,  which  was, at  that  time,  still  regarded  as  non- 
fossiliferous.  This  latter  innovation  of  Murchison's,  though 
adopted  by  BaiTande,  and  by  the  geological  survey  of  Great 
Britain,  who  have  been  copied  in  Canada  and  the  United 
States,  is  with  reason  rejected  by  most  other  British  geolo- 
gists, and  by  those  of  Sweden,  who  retain  the  name  of 
Canibrian  for  both  the  Lower  and  the  Middle  groups  of 
Sedgwick.  Belt,  (avIio  with  Hicks,  has  greatly  advanced 
our  knowledge  of  these  older  rocks  in  Great  Britain,)  in- 
cludps  T  and  II  of  the  above  table  in  the  Lower  Cambrian, 
while  he  gives  to  III,  lY,  and  V  the  name  of  Upper  Cam- 
brian, conceding  for  the  original  Upper  Caml)rian  of  Sedg- 
wick, (the  Siluro-Cambrian),  the  name  of  Lower  Silui-ian, 
a  nomenclature  wliich  Avas  adopted  by  Lyell.  In  these 
pages,  while  maintaining  the  name  of  Siluro-Cambrian,  the 
terms  Lower  and  Upper  Cambrian  will  be  used  in  the  sense 
in  Avhich  they  are  employed  by  Belt  and  by  llicks. 

§  2r)2.  The  whole  of  the  Lower  and  Upper  Cambrian  in 
Wales,  amounting  to  over  10,000  feet,  consists,  so  far  as 
known,  of  vsandstones,  conglomerates,  and  phales.  The 
latter  are  sometimes  calcareous,  but  no  limestone  beds  have 
been  found  below  the  Llandeilo  group  of  the  Siluro-Cam- 
brian. The  Upper  Cambrian  series,  which  has  been  care- 
fully studied  and  sub-divided  by  Belt,  presents,  accoi-ding 
to  him,  a  remarkable  case  of  inversion  at  Dolgelly,  m  Noi-tli 
AVales,  where  the  strata  are  completely  overturned,  so  that 
theapi)arent  succession,  in  ascending  order,  gives  the  Areing, 
Tremadoc,  Dolgelly,  and  Festiniog  foi'mations.  Great  dislo- 
cations occur  in  South  Wales,  by  which  the  Tremadoc,  and 
even  the  Arenig  rocks,  are  let  down  against  the  Harlech 
beds  of  the  Longraynd  group.  For  a  more  detailed  account 
of  the  Avhole  question  of  the  discovery  and  the  nomencla- 
[E.  9] 


m 


■ 


m 


Ml 


130   E.       SPECIAL    REPORT.      T.   STEKRY  HUNT,   1875. 

ture  of  these  older  rocks,  the  reader  is  r(;ferred  to  the 
author's  essay  on  The  History  of  Canibrian  and  Silurian. 
(Chem.  and  Geol.  Essays,  pa<i:es  349-425.) 

§  253.  The  fauna  found  in  the  Menevian  of  South  Wales, 
including  species  of  Paradoxldes,  Mlcrodisciis,  Conocory- 
phe,  1^=  Couocephalus  and  Conocephalites,)  and  Agnosius, 
is  continued  downward,  with  but  little  change,  through  more 
than  2,000  feet  of  the  underlying  Ihirlech  rocks,  which  are, 
moreover,  connected  with  the  Menevian  by  several  species  of 
brachiopods  common  to  l)oth,  and  have  liere  a  measured 
thickness  of  nearly  4,000  feet.  The  ]f)wor  x^ortion  of  the 
Harlech,  which  consists  chiefly  of  red  and  green  sandstones, 
with  slaty  beds,  resting  unconforniably  upon  crystalline 
rocks,  and  measuring  1,000  fet.'t  in  thickness,  has,  however, 
yielded  no  trilobites,  though  containing  Leperditla^  Bis- 
cina,  Oholella,  and  Lingulella.  This  absence  of  trilobites 
from  the  base  of  the  Cambrian  seems  to  mark  a  distinct  zcme, 
of  wiiich  we  have  further  evidences  both  in  Scandinavia 
and  in  Bohemia. 

§  254.  We  find  in  Sweden  the  whole  succession  of  British 
Cambrian  and  Silurian  rocks  represented  by  about  1,000 
feet  of  horizontal  stratn,  which,  according  to  Linnarsson, 
may  be  thus  designated,  as  nund)ered  in  descending  order. 
(Geol.  Magazine,  1870,  vol  III,  page  240.) 


1.  Encrinurus  bods. 

2.  Lcpticna  limestone. 

3.  Upper  Graptdlitic  schists. 

4.  Bracliiopod  seliists. 

5.  Trinucleus  sehists. 

6.  Cliasinops  limestone. 

7.  isriddlo  (Jraptolitio  sclilsts. 

8.  Orthocoras  limestone. 


9.  T.owcr  Graptolitic  schists. 

10.  Corati)[)yj^e  limestone. 

1 1 .  Di(;tyi)nema  schists. 
1-,  Olcmis  s(!liiHts. 

l.'i.  Paradoxidcs  soliists. 

14.  Fucoidal  sandstone. 

1.5.  Eopliyton  sandstone. 

— .  Unconformablo  crystalline  roclts. 


§  255.  The  Olenus  schists,  which,  in  some  parts  of  Swe- 
den, are  not  over  forty  or  iifty  feet  in  thickness,  contain,  it 
is  said,  the  equivalents  of  the  three  divisions  of  the  5,000 
feet  of  the  British  Lingula  flags,  and  are  underlaid  by  the 
Paradoxides  schists,  which  are  by  Linnarsson  regarded  as 
representing  both  the  Menevian  and  the  trilobitic  poi'tions 
of  the  Iliirlech.  The  sandstones  14  niid  15,  which  form  the 
lower  divisions  of  the  Swedish  Lower  Cambrian,  may,  there- 


CAMBKIAN   OF   SWEDEN   AND   NOUWAY, 


E.    131 


fore,  reasonably  be  supposed  to  represent  the  inferior  por- 
tion of  the  Harlech.  Thev  measure  about  loo  feet  in  mid- 
die  Sweden,  but  are  thicker  both  to  the  north  and  the  south. 

§  256.  These  sandstones,  according  to  Linnarsson,  are 
marked  by  the  absence  of  trilobites,  and  in  Sweden  the 
upper  division,  the  Fucoidal  sandstone,  contains,  besides 
impressions  of  algse,  and  tracks  and  furrows  of  worms  and 
other  animals,  only  two  species  of  Lingulellidje.  The  un- 
derlying Eophyton  sandstone  has  yielded  a  more  marked 
fauna ;  besides  Cruzlana,  Harlanla  {Arthrophycus)  and 
Eophyton,  all  of  which  Linnarsson  regards,  with  reason,  as 
but  casts  and  tracks,  of  little  significance,  we  find  a  brach- 
iopod,  provisionally  called  Oholas  or  Lingida  monilifer, 
unknown  elsewhere,  which  will  probably  constitute  a  new 
genus,  besides  Hyolitlies  leviyatas  and  Astylospongia  radi- 
ata,  which  have  apparently  "no  near  relatives, "  It  is  from 
this  Eophyton  sandstone  that  Torell  has  described  vertical 
funnel-shaped  casts,  occurring  in  groups,  which  he  regards 
as  formed  by  two  species  of  animals,  named  by  him  Mono- 
crater  ion  and  Diplocraterion.  Around  the  summit  of  the 
former  are  impressions  of  what  seem  to  be  tentacles. 

§  257.  The  corresponding  rocks  in  southern  Norway  are, 
by  Kjernlf,  divided  into  seven  groups  or  stages.  Stage  1  of 
this  author  is  a  great  mass  (2,000  feet  or  more)  of  red  and 
gray  sandstones  and  conglomerates,  (sparagmites,)  with 
clay-slates  of  the  same  (!olor,  besides  a  bluish  quartz-rock, 
quartzy  talcose  slates,  and  considerable  beds  of  limestone 
and  dolomite;  the  whole  Avithout  observed  fossils,  and  called 
by  Kjernlf,  Lower  Taconic.  Stage  2  consists  of  clay- 
slates  and  limestones,  with  Didyonernd  and  Olenns,  and  is 
designated,  by  Kjerulf,  Upper  Taconic,  to  which  period, 
moreover,  he  refers,  with  some  doubt,  a  great  mass  of 
hornblendic  and  other  crystalline  schists.  Of  the  suc- 
ceeding groups,  called  by  him  Silurian,  Stage  3  includes 
the  older  Graptolitic  schists  and  the  Orthoceratite  lime- 
stone ;  Stage  4,  the  Chasmops  limestone  ;  Stage  5,  calca- 
reous sandstones  and  shales,  and  Stages  6  and  7,  the  newer 
Graptolitic  schists  and  Pentamerus  limestones.  The  rela- 
tions of  these  stages  with  the  Swedish  series  are,  for  the 


'4 


|iS 


Ml 


ifi 

I 


132   E.      SEPCIAL    REPORT.      T.  STERRY  HUNT,  IS?."). 

most  part,  evident.  Stage  1  is  supposed  to  be  equivalent 
to  tlie  basal  sandstones  of  Sweden  ;  but,  from  their  thick- 
ness and  their  lithogical  peculiarities,  these  Lower  Taconic 
rocks  of  Kjerulf  may  not  improbably  include  also  a  still 
lower  horizon. 

For  the  facts  with  regard  to  these  rocks,  th<'  present 
writer  is  indel)ted,  in  part,  to  the  unpublished  maps  and 
sections  exhibited  by  the  geological  survey  of  Norway,  at 
Philadelphia,  in  187(5.  lie  has  also  to  acknowledge  per- 
sonal communications  on  the  geology  of  these  regions  from 
his  friends,  Di-.  KjiMull"  and  Dr.  Torell,  the  dii'ectors,  re- 
spectively of  the  geological  survey  of  Norway  and  Sweden. 

§  258.  In  Russia,  a  ))and  of  pyroschist.s  wliich,  by  the 
presence  of  DiHi/onemaJlabelliforme,  are  identilied  by  Lin- 
narsson  with  tli(3 1)icty(mema  schists  of  Sweden,  (regarded 
as  the  equivalent  of  the  Tremadoc  group  of  Wales,)  ex- 
tends from  St.  Petersburg  along  the  coast  of  Esthonia,  and 
has  beneath  it  several  hundred  feet  of  friable  sandstones 
and  shalea,  including  the  Obolus  or  Ungulite  grit.  But 
little,  however,  is  as  yet  known  of  the  fauna  of  these  basal 
sandstones. 

§  259.  In  Bohemia,  the  fauna  of  the  so-called  Primordial 
zone  (Stage  C  of  Barrande,)  is,  according  to  Linnarsson,  most 
closely  related  with  that  of  the  middle  portions  of  the  Par- 
adoxides  schists  of  Sweden.  Between  this  and  the  Stage 
A  of  Barrande,  which  consists  of  crystalline  rocks,  is  las 
Stage  B,  a  series  of  sandstones  and  conglomerat(^s  which 
contain  the  casts  of  double  tubes,  supposed  to  be  due  to 
annelids.  Thus  it  appears  that  in  Bohemia  as  in  Scanda- 
navia,  and  in  Wales  and  Canada,  there  exists  a  seiies  of 
sandstones  and  slates  beneath  the  lowest  recognized  trilol)itic 
horizon. 

§  200.  We  may  now  inquire  what  data  the  Cambrian 
rocks  of  Great  Bi'itain  and  of  continental  Europe  can 
alford  for  a  comparison  with  those  of  North  Amei-ica  {  The 
genera  of  trilobites  found  in  the  Longmynd  are  Atpiostus^ 
Conocoryphe.,  MUrodiscus^  Paradoxides,  and  Phdonia, 
all  of  which,  with  the  excej^tion  of  the  last,  occur  in  the 
Menevian,  with   the  addition  of   ArioneUus.     The  genus 


GEOLOGICAL   HISTORY   OF   GRAPTOLITES.         E.    133 


Olenus  extends  from  the  base  of  the  Lingiila  Hags  to  the 
Lower  Arenig,  which  latter  also  contains  Ampyx^  Asaphiis^ 
Cahjmene,  Cheirurus,  and  Dikellocephalus.  The  last- 
named  genus,  according  to  Ilicks,  is  not  found  below  the 
Arenig,  the  forms  hitherto  referred  to  it  in  the  Tremadoc 
and  the  Lingula  Hags  belonging  to  the  allied  genus  JVeseu- 
retus.  The  genus  (Jonororyphe  is  confined,  so  far  as  known, 
to  the  Longmynd  and  Menevian,  and  the  various  species 
referred  to  it  from  higher  horizons  should,  according  to 
Belt  and  Hicks,  constitute  a  new  genus.  Agnostus^  which 
extends  from  the  Longmynd  to  the  Arenig,  is  thus  the  only 
genus  of  trilobites  which  connects  the  Lower  with  the  Upper 
Cambrian. 

No  gasteropods  have  been  found  below  the  Middle  Arenig, 
and  no  lamellibranchs  below  the  Tremadoc.  Orthoceras 
occurs  in  the  Tremadoc,  and  with  Cyrioceras  in  the  Lower 
Arenig.  Dendrocrinus  and  Paleasierina  have  been  found 
in  the  Tremadoc,  while  a  cystidean  is  met  with  in  the  Me- 
nevian, and  in  Sweden  a  form  of  star-fish  occurs  in  rocks 
regarded  as  the  equivalent  of  the  Longmynd.  The  genus 
Oholella  extends  from  the  Longmynd  to  the  Arenig.  Most 
of  the  above  facts  relating  to  the  Cambrian  fauna  of  Wales 
are  taken  from  the  late  papers  of  Hicks,  already  cited. 

§  261.  The  study  of  the  graptolites,  as  a  means  of  fixing 
geological  horizons,  has,  of  late,  attracted  considerat)le  at- 
tention, and  the  researches  of  Linnarsson  have  recently 
enabled  Nicholson  to  make  very  satisfactory  comparisons 
between  the  graptolite-bearing  strata  of  Sweden  and  those 
of  Great  Britain.  (Geol.  Magazine  for  1870,  Vol.  XTTI,  page 
245.)  There  are,  according  to  Linnarsson,  five  graptolitic 
zones  in  the  paleozoic  rocks  of  Sweden,  the  first  of  whicii. 
in  ascending  order,  (referring  to  the  table  in  §  254),  is  tliat 
of  the  Olenus  and  Dictyonema  schists  (12,  11),  (character- 
ized by  Dictyonema  Jlabelli/orme^  and  DicUoyraptaH  tenel- 
lus,)  regarded  by  Nicholson  as  equivalent  to  the  Tremadoc 
group.  The  second  zone,  designated  l)y  Linnarsson  as  the 
Lower  Graptolitic  shales  (9),  c(mtains  Tetrayraptus,  D'uly- 
mograj)tus,  and  ritytloyraptiis.  These  are  the  undoubted 
equivalents  of    the    Skiddaw  (Cumberland)  and   Quebec 


W 
i 


f 


¥ 


134   E.      SPECIAL   KEPOKT.      T.  STEHIIY  HUNT,  1875. 


Hi 


' 


graptolitic  shales,  and  correspond  to  tlie  Areniu-  uroup  in 
Wales,  which  contains  them  thronghout,  though  most 
abundantly  in  its  lower  divisions.  The  third,  or  Middle 
Graptolitic  schists  (7)  correspond,  according  to  Nicholson, 
to  those  found  in  the  lower  portions  of  the  Moffat  series  in 
the  south  of  Scotland,  and  the  fourth  andf/th,  (includ<>d  in 
the  Upper  Graptolitic  schists,  3,)  to  the  superior  poi'tion  of 
the  same  series. 

The  schists  of  division  3,  in  Sweden,  include,  according 
to  Nicholson,  two  distinct  graptolitic  zones,  the  lower  part 
containing  the  forms  of  the  Ccmiston  mndstones  of  Cum- 
bci'land,  regarded  as  belonging  to  the  Siluro-Cambrian; 
while  the  upper  part  yields  the  forms  of  the  Coniston  grits, 
the  equivalents  of  the  May-Hill  sandstone,  above  the  Bala 
group,  and  belonging  to  the  true  Silurian.  This  upjier  por- 
tion, which  constitutes  the  Ji/ih  graptolitic  zone,  is  well  de- 
veloped in  Norway.  It  would  be  foreign  to  the  j^urposes  of 
our  history  to  enter  into  further  details  with  regard  to  these 
higher  graptolitic  zones,  whi(;h  apparently  correspond  to 
those  of  the  Utica  and  Clinton  formations  of  North 
America. 

§  202.  Returning  now  to  the  lower  paleozoic  rocks  of  the 
New  York  series,  we  have  seen  that  Billings,  conceiving  that 
the  Olenellus  beds  of  Vermont  and  Newfoundland  belong 
to  a  lower  horizon  than  the  typical  Potsdam  sandstone  of 
New  York,  designated  this  as  Upper  Potsdam.  This  for- 
mation, as  is  w^ell  known,  is  traced  continuously  from  the 
southern  base  of  the  Adirondacks  into  tin?  Ottawa  basin  in 
central  Canada  ;  to  the  east  and  west  of  which  it  disappears 
along  the  northern  outcrops  of  the  paleozoic  series.  So  far 
as  yet  observed,  it  rests  in  a  nearly  horizontal  attitude  upon 
the  Eozoic  crystalline  rocks,  and  in  Ilemmingford  Moun- 
tain, near  the  north-west  border  of  Lake  (Jhamplain,  where 
it  reaches  its  greatest  observed  thickness,  of  about  600  feet, 
includes  l)edsof  a  conglomerate  holding  jiebblcs  of  quartz, 
and  others  of  green  and  blackish  argillite.  The  rock  is 
sometimes  a  friable  sandstone,  and  at  other  times,  a  hard 
and  almost  vitreous  quai'tzite,  white,  and  rarely  red  in  color. 
Towards  the  summit  it  becomes  interstratified  with  dolo- 


ri 


GEOLOGICAL   HISTORY    OF   SCOLITIIUS. 


E.  135 


mitic  layers,  marking  its  passaije  into  the  suceerdinu'  Mag- 
nesian  limestone,  which,  from  its  rough  surface  and  its  fee- 
ble (^ffervHsence  with  acids,  was  early  misnamed  the  Calci- 
ferous  sandrock.  It  is,  howevei-,  a  true  dolomite,  granular 
in  texture,  and  abounding  in  druses  holding  crystals  of 
quartz,  calcite,  suli)hates  of  baryta  and  stroutia,  and  in 
some  plac(^s  small  nodules  of  gypsum.  Ft  often  passes  to- 
wards the  summit  into  an  impure  argillite,  and  has  a  maxi- 
mum thickness  of  300  feet. 

§  203.  The  organic  remains  found  in  the  Potsdam  of  the 
above  defined  area,  are  few  in  nuiubci" ;  besides  two  species 
of  Lingida,  it  has  yielded  at  Keeseville,  New  York,  a  trilo- 
bite,  at  first  called  a  Calymene,,  but  sul)sequently  described 
by  Bradley  as  Conoccpliardea  {Conocoryphe)  iiibiutus, 
which  is  associated  with  a  species  of  Ht/olit/ics^  a  Pleuroto- 
maria  and  ci-inoidal  fragments.  A  species  of  DiJielloce- 
phalus  lik<'  D.  Sesoslrif<  is,  according  to  Billings,  met  with 
in  the  superior  beds  of  the  Potsdam,  at  Whitehall,  N(;w 
York,  while  at  Beverley,  Ontario,  along  with  Liiiynhi  acu- 
minata^ are  found  a  Pleurotomaria^  an  Opliileta,  and  two 
species  of  Orthoceras^  besides  marks  of  alg{c.  Billings, 
however,  remarks  that  these  beds  should  perhaps  be  in- 
cluded in  the  overlying  Calciferous  sandrock.  In  several 
localities  in  Canada,  the  beds  of  the  Potsdam  bear  the 
tracks  of  large  animals  of  several  species,  which  have  been 
named  Protiahnifes  and  Climactlchnitcs,  both  of  which  are 
i-egarded  as  probably  due  to  crustaceans.  (Pal.  Fossils,  I, 
pages  57,  59,  97,  198.) 

§  264.  In  addition  to  these,  the  upper  part  of  the  forma- 
tion is  found  to  be  abundantly  nmrked,  over  considerable 
surfaces,  by  a  form  descrilx'd  by  Billings  under  the  name 
of  Scolilkus  Canadensis.  ''This  sx)ecies  consists  of  cylindri- 
cal or  irregular  prismatic  stems  (or  rather  the  cavities  in 
the  rock  once  occupied  by  such  stems)  from  one  to  two  lines 
in  diameter,  and  from  one  to  six  inches  in  length,  and  eithr-r 
straight  or  more  or  less  curved.  In  some  specimens  several 
of  the  stems  are  in  contact  with  each  other,  and  when  this 
is  the  case,  and  the  stems  have  an  angular  shape,  they  very 
much  resemble  the  coral,  Tetradhiin 


Tlie  larger  stems  are 


VM   E.      SPECIAL    UKPOltT.      T.  STEUUY  HUNT,  1875. 


Nm 


more  often  straight  than  the;  smaller.  The  individuals  are 
usually  scattered  irregularly  through  the  rock,  lying  in  all 
diivctions."     (Ibid.,  I,  00.) 

'IMic  l^i-olit/inti  appears  on  the  weathered  surface  of  the 
l)e(ls  "in  the  form  of  small  holes,  which  sometimes  pene- 
tnite  vei'tically  to  a  depth  of  several  inches,  but  on  break- 
ing up  the  rock  they  are  found  to  be  more  or  less  cun'ed  in 
(lill'crent  directions,  and  often  irregularly  contorted,  and  in- 
termingled with  eacli  other.  The  casts  of  the  interior  of 
these  cavities,  in  freshly  broken  or  unweathered  specimens 
of  the  rock,  usually  appear  as  cylindrical  or  angular  rods, 
(with  three,  four  or  live  sides,)  composed  ai)parently  of 
grains  of  sand  cemented  by  a  slightly  calcareous  matter, 
more  or  less  tinged  with  oxyd  of  iron.  The  origin  of  tliese 
holes  is  not  quite  certain  ;  some  suppose  them  to  be  re- 
mains of  fucoids,  others  of  corals,  while  many  are  of  opin- 
ion that  tliey  were  the  habitations  of  small  burrowing  ma- 
rine or  shore-frequenting  animals.  Whatever  may  have 
been  their  origin,  they  characteriyx'  only  the  upper  part  of 
tlie  Potsdam  sandstone.  The  original  specimens,  upon 
which  the  genus  Scolithus  was  established,  differ  from 
those  above  described  in  being  straight,  and  more  decidedly 
cylindrical,  and  are  therefore  probably  a  distinct  species.'' 
A  ligure  of  Seollihun  Canadensis  is  given  in  the  Geology  of 
Canada,  page  102,  from  which  the  above  account  is  quoted. 

§  20.").  The  name  of  H/iol/i/ius  was  proposed  by  S.  S.  llal- 
deman,  in  1840,  as  the  designation  of  a  sub-genus  of  fuccjids, 
and  was  applied  by  liim  to  the  cylindrical  casts  found  in  the 
Primal  white  sandstone  at  Chiques,  on  the  Susquehanna. 
In  1847,  Professor  James  Hall  described  ScoliUius  linearis^ 
giving  a  ligure  of  one  specimen  from  the  J'usquehanna,  of  an- 
other from  North  Adams,  Massachusetts,  and  of  a  third 
from  a  locality  not  named.     It  was  said  to  be  found  vMfoly 


on  Lake  Champlain,  but  was  refeiTed  to  the 
stone,  and  declared  to  occur  in  sandstones  ■ 
base  of  the  Green  Mountains,  as 
Pennsylvania,  and  Virginia.     (Paleo.     ilogy 
vol.  I,  pag(;  2,  and  plate  I,  ligs.  1  a — 1  c. 
§  2GG.  Markings  called  Sculiihus^  have  sin 


•w 
.S'ew 


md- 

the 

rsey, 

York, 


to 


been  looked 


OEOUXilCAL    HISTOUY    OF   SCOLITHUS. 


E.    137 


[I. 

k 
II- 

Id 


upon  as  evidences  of  existence  of  tlie  Pofsdani  sandstone  in 
various  localities  tlirouf;liout  the  Aiipalacliian  valley,  and  in 
l*tMinsylvania  were  described  by  II.  1).  Rofrm-s  as  character- 
istic of  the  Primal  white  sandstone,  which  wa;s  regarded  as 
the  equivalent  of  the  Potsdam,  (§4,  7,  9.)  The  name  of  7V 
huliles  which,  according  to  Rogers,  was  given  to  these  mark- 
ings in  the  annual  geological  reports  of  Virginia  and  Penn- 
sylvania, was  subsequently  exchanged  for  tliatof  Scollthufi 
linearis.  The  original  description  of  this  species  by  llall 
was  amiilified  and  augmented  by  Rog^'rs,  who  describes  it 
as  "a  nearly  straight  cylindrical  simph.' stem-like  impres- 
sion, nsually  almost  smooth,  but  in  some  specimens  faintly 
waved  or  grooved  transversely  to  its  axis.  Its  diameter  is 
from  one  eighth  to  one  half  an  inch,  its  length  from  a  few 
inches  to  two  or  three  feet.  Its  position  in  the  rock  is  in- 
variably perpendicular  to  the  bedding,  suggesting  the  idea 
of  perforations  by  some  marine  worms.  One  end  of  the  fos- 
sil always  terminates  at  the  upper  surface  of  th(!  bed  of  sand- 
stone inclosing  it,  and  nsually  in  a  rudely-llattened  knob 
or  head,  giving  to  the  whole  the  likeness  of  a  large  long  pin. 
This  knob  is  probably  a  cast  formed  in  the  wide,  conical, 
funnel-shaped  mouth  of  a  cylindrical  perforation.  Similar 
stem-like  forms  occnr  in  some  of  the  other  sandstones  of  the 
liigher  Apx)alachian  fonnations,  but  none  are  so  well  char- 
acterized as  this  si)ecies  of  the  Primal  white  sandstone.  An 
excellent  locality  is  at  Chiques,  on  the  Susquehanna."  A 
figure  is  given  by  Rogers  of  this  fossil,  which  is  also  said  to 
occur  in  great  abundance  in  the  Blue  Ridge  of  Virginia. 
(Geol.  Penn.,  II,  815.) 

§  2G7.  In  isr)2,  TIall  described  and  figured,  under  the  name 
of  Scolilhus  Terticalis,  a  form  characterized  as  being  smaller 
than  S.  linearis,  and  as  penetrating  vertically  the  beds 
of  the  ^Medina  sandstone  in  Monroe  county.  New  York. 
(Paleontology  of  New  York,  vol.  II,  page  G,  and  plate  II, 
figure  8.)  It  was  not  until  1862  that  Billings  described 
S.  Canadensis,  (§  204,)  at  the  same  time  declaring  with  re- 
gard to /S^.  linearis,  "it  is  generally  larger,  and  the  stems 
are  straight  and  parallel  with  each  other,"  and  adding,  "I 
have  seen  no  specimens  of  this  species  m  the  Canadian 


4 


ilM. 


im 


I 


138   E.       SPECIAL    KEPORT.      T.  STERRY  HUNT,   1875. 

rocks,  though  it  occurs  in  tlie  lowest  red  sandstone  of  La- 
brador, on  the  strait  of  Bellisle."'  Tliis  sandstone,  already 
noticed,  (§  215)  is  below  the  Olenellus  limestone,  and  of  the 
Srolii/ius  therein  found  Billings  elsewhere  remarks,  that  "it 
(lillV^rs  from  the  one  so  common  in  the  Potsdam  sandstone 
of  Canada,  in  being  larger  and  straighter.  It  is  perfectly 
identical  witii  that  of  the  Upper  Primal  sandstone  of  Penn- 
sylvania, and  also  with  that  of  the  Potsdam  (Chilhowee) 
sandstone  of  Tennessee."     (Pal.  Fossils,  III,  2,  96.) 

§  268.  Several  examples  of  ScoUthus  which  the  present 
writer  has  examined  from  the  Potsdam  sandstone  of  Wis- 
consin, appear  to  be  identical  with  aS*.  Canadetisis  and, 
though  pi'obabl y  distinct,  are  much  more  like  to  the  L.  verti- 
calls  collected  by  him  in  the  Medina  (Levant)  sandstone  of 
Huntingdon  county,  Pennsylvania,  than  to  the  aS*.  linearis 
found  in  the  Primal  white  sandstone  along  the  Susque- 
hanna and  the  Schuylkill.  Some  specimens  from  these  lat- 
ter localities  exhibit,  in  a  marked  manner,  the  transversely 
"waved  or  grooved"  surface,  noticed  by  Rogers,  leading 
an  eminent  foreign  geologist,  who  lately  saw  them  for  the 
iirst  time,  to  take  them  foi'  casts  of  crinoidal  stems. 

§  269.  Further  investigations  are  however  heeded  to  clear 
up  the  history  of  Scolii/n/s,  and  it  would  appear  that  even 
in  the  typical  Potsdam  sandstone  there  have  been  con- 
founded under  this  name  the  marks  of  distinct  and  unlike 
objects.  The  sandstone  which  at  Port  Henry,  NV^w  Yoi'k, 
forms  the  base  of  the  Champlain  series  is,  in  its  lower  por- 
tions, a  strong,  hard,  massive,  thick-bedded,  dark  bluish 
or  iron-gray  quartzite,  with  lighter  gray  layers,  and  includes 
thin  blackish  shaly  partings.  The  higher  portions  are 
thinner  bedded,  light-gray  and  porous,  and  are  made  up 
of  strongly  coherent  rounded  agglutinated  grains,  with 
irregular  iut«M'sticPS.  the  wdiolc  being  silicious.  and  siighrly 
stained  with  inm-oxyd.  Hall  has  noted  the  same  structui'e 
in  (he  ujiper  beds  of  the  Potsdam  in  Iowa,  and  has  well  re- 
marked that  their  appearance  suggests  that  they  were 
"largely  formed  from  silica  in  solution,  or  fi'om  gelatinous 
silica."     (Paleontology,  Vol.  Ill,  page  4.) 

§  270.  Some  of  these  ux>per  beds  at  Port  Henry^  lately 


i    '■^iul 


vr 


HISTORY    OF   THE    CIIAZY    FOKMATION. 


E.   i;39 


examined  by  the  writer,  abound  in  impressions  evidently 
oro;anic,  which  have  been  designated  S'coh'/kus.  These 
appear  iqjon  the  iq^per  surface  of  the  newly  sei)arated  beds 
as  cylindrical  cavities,  each  enclosing  a  centi-nl  tube  made 
up,  like  the  surrounding  rock,  of  coherent  silicioiis  griiins. 
These  tubes  are  a  millimeter  in  intei-nal  diameter,  with 
walls  half  a  nuUimeter  in  diameter,  and  a  vacant  space  of 
the  same  dimension  between  the  tube  and  the  smooth  sur- 
rounding walls  of  the  cavity;  thougli  vciy  fragile,  the  in- 
terior tubes  were  disclosed  in  oblique  fiactures  of  the  rock 
to  the  length  of  a  centimeter,  without  any  marks  of  joints 
or  Septa.  They  exhibited,  in  some  cases,  traces  of  two  con- 
centric layers.  The  cylinders  were  seen  to  ti-a verse  vertically 
the  beds  for  distances  of  two  oi'  three  inches,  but  the  lower 
portions  were  tilled  up  and  their  internal  structure  was  not 
aj^parent.  The  arrangement  is  such  as  would  result  from 
the  enclosui'e  in  the  rock  of  a  cylinder  having  a  centi'al  axis, 
with  an  intermedia  t';  space  v/hich  became  tilled  with  silicious 
matter,  the  cylind -r,  and  its  axis  being  subsequently  re- 
moved. 

In  weathered  specimens,  from  which  the  internal  rube  lias 
disappeared,  the  cylindrical  cavities,  more  or  less  completely 
filled,  resemble  very  juuch  the  burrowings  of  a  woi'm,  l)ut 
in  either  condition  they  are  evidently  very  distinct,  l)oth 
from  the  ]irisinatic  shapes  not'ced  by  Billings  under  tlie 
name  of  Scolilhiis  CamuUnsif^  (^'2(54, )  and  tin*  transversely 
grooved  cylindrical  rods  of  the  Pfimal  white  sandstone. 

^271.  We  have  already  seen  that,  while  tli(»  Potsdam 
sandstone  graduates  into  the  Calciferous  sand-iock.  the 
overlying  Chazy  foi-mation  gives  eviilence  of  a  break  in  the 
succession  of  sediments;  its  base,  in  parts  of  the  Ottawa 
basin,  consisting  of  a  limestone-conglomei'ate,  resting  on  the 
Calciferous  sand-i'ock.  I'Jsewlx're  in  this  region,  it  apjx-ars 
as  a  silicious  conglomerate,  with  (iiiaitz  {)ebl)les,  nodnles  of 
phosphate  of  lime,  (coprolitesj  and  the  characteristic  fossils 
of  the  Chazy  formation,  resting  directly  on  the  Laurentian 
gneiss;  while  in  Herkimer  county.  New  \  u\k.  the  Chazy 
is  absent  from  its  place  heiwt'en  the  Calciferous  and  the 
Trenton.     At    Grenville,  on    the    Ottawa,   there    is    found 


140    E.       SPECIAL    REPORT.       T.  STERRY  HUNT,  1875. 


above  the  limestone-conglomerate  of  the  Chazy  about  fifty 
feet  of  grayish  sandstone,  sometimes  ripple-marked,  and 
occasionally  conglomerate.  These  are  accompanied  and  fol- 
lowed by  greenish  fucoidal  shales,  above  which,  making  the 
npper  portion  of  the  Chazy  formation,  is  a  reddisli  or  gray- 
ish jiure  massive  limestone,  composed,  in  great  part,  of  the 
crystalline  remains  of  crinoids  and  cj^stideans,  while  other 
beds  abound  in  brachiopods.  These  limestones,  which  are 
sometimes  interstratified  with  dolomitic  layers,  have  at  Mon- 
treal, where  they  are  largely  quarried  for  l^uilding-purposes, 
a  thickness  of  seventy  feet,  the  aggregate  of  the  whole  Chazy 
formation  in  the  region  being  about  IHO  feet.  • 

§  272.  The  Chazy,  after  disappearing  beneath  the  border 
of  the  Trenton,  a  little  to  the  north-east  of  Montreal,  (§  244,) 
re-appears  oOO  miles  further  on  in  the  same  direction,  on  the 
Mingtui  Islands  in  the  gulf  of  St.  Lawrence,  where  it  is  rep- 
resented by  a  series  of  fossil iferous  limestones,  witli  some 
interposed  sandstones  and  shales,  the  whole  thickness  being 
estimated  at  about  300  feet.  The  underlying  beds,  supposed 
to  represent  the  Calcii'erous  sand- rock,  are  also  highly  fos- 
siliferous  magnesian  limestones,  of  which  about  250  feet 
have  been  observed.  (Geology  of  Canada,  chapters  VII  nnd 
VIII.) 

§  2?;}.  In  the  northern  part  of  Lake  Huron,  horizontal 
liiiiestones,  dolomitic  at  the  base,  and  fossiliferous  through- 
out, are  L'ouud  resting,  at  the  Snake  Islands,  ou  the  up- 
turned Iluronian  strata,  while  at  Lacloche  Island,  and  fur- 
ther to  the  west,  similar  limestones  repose  ui)on  hoi-izontal 
beds  of  red  and  white  sandstone,  known  as  the  St.  Mary's 
sandstone.  These  limestones  have  yielded  the  organic  re- 
mains of  the  Birdseye,  Black  lliver,  and  Trenton  divisions 
of  the  Trenton  grou)),  and  in  Sugar  Island,  according  to 
Professor  Hall,  have  at  their  base  some  arenaceous  and 
argillaceous  beds,  which  contain  the  chai'acteristic  fossils 
of  the  Chazy  formation.  (Foster  and  Whitney,  Geology 
of  Lake  Superior,  II,  140.) 

§  274.  To  tlu'  south-west  of  Lake  Superior,  In  Wisconsin, 
Minnesota  and  Iowa,  in  the  upper  Mississippi  valley,  we 
find  i'ep<...e(l,  with  some  variations,  the  rocks  of  tluKMiam- 


CAMBRIAN    OF   THE    MISSISSIPPI    VALLEY.        E.    141 


I 

I 

I 
t5 


ital 

llp- 

u  I'- 
ll :i] 
•y's 

OllS 

to 
111(1 

dls 

in, 
we 
Ill- 


plain  division  of  the  New  York  series.  These  rocks  iiave 
been  studied  bv  David  J).  Owen,  bv  James  Hall,  and  later 
by  lloland  Irving.  In  Wisconsin,  where  these  strata  occu- 
py a  large  area  to  the  west  and  south  of  tlie  crystalline 
rocks,  the  Potsdam  sandstone  is  desciil)ed  as  liaving  a 
maximum  tliickness  of  about  700  feet,  and  as  overlaid  by 
the  Lower  Magnesian  limestone  of  Owen.  It  however  thins 
out  to  tlie  northward,  where  the  limestone  rests  directlv  on 
the  crystalline  strata.  It  was  noticed  by  Hall  that  tlie  up- 
per part  of  the  Potsdam  becomes  dolomitic,  showing  a  pass- 
age to  the  overlying  formation,  and  this  transition  lias  since 
been  studied  by  Irving,  in  Dane  and  Columbia  counties. 
He  describes  there  800  feet  of  sandstone,  which  have  been 
penetrated  in  borings,  and  sliow  more  or  less  dolomitic  ad- 
mixture for  the  upper  two  thirds.  Above  this  lie  about 
thirty  feet  of  a  yellowish  magnesian  limestone,  massive  be- 
low and  shaly  above.  It  includes  layers  of  green-sand, 
especially  near  its  base,  and  in  places  abounds  in  trilobites, 
tlie  most  common  of  which  is  DikeUoccjjJialn.s  J///ni(,sofrn- 
sis.  Tliis  division,  called  by  Irving  the  Mendota  limestone, 
is  succeeded  by  tliirty-hve  feet  of  sandstone,  often  purely 
silicious,  but  sometimes  ferruginous  and  dolomitic.  To  this 
division,  wliich  extends  over  wide  areas,  the  name  of  the 
Madison  sandstone  is  given.  Above  this  occurs  the  main 
body  of  tlie  Lower  Magnesian  limestone,  from  eighty  to  li?0 
feet  in  thickness,  including,  at  its  base,  a  persistent  stratum 
of  oolitic  silicious  rock,  and  layers  of  green-sand,  and  con- 
sisting above  chiefly  of  cherty  dolomite.  Tliis,  which  is 
sometimes  geodiferous,  contains  small  quantities  of  lead  ore, 
and  very  few  organic  remains. 

The  glauconite  or  green-sand  from  tliese  ancient  rocks 
closely  resembles  that  from  the  cretaceous  strata  of  New 
Jersey.  An  analysis,  by  the  writer,  of  a  siH'cimen  collected 
by  Professor  Hall  at  Red  Bird  in  Minnesota,  gave  silica, 
44.58  ;  protoxyd  of  iron,  20.01  ;  magnesia,  1.27  ;  lime,  2.4!) ; 
alumina,  11.45;  potash,  G.9G;  soda,  0.98;  Avater,  9.00  = 
100.00.  (Report  of  Geological  Survey  of  Canada,  180:3-00, 
page  232.) 

§  275.  The  Lower  Magnesian  limestone  is  directly  overlaid 


^s* 


m 


v. 


142   E.      SPECIAL   REPORT.      T.  STEKRY  HUNT,  1875. 

by  the  St.  Peter's  sandstone  of  Owen.  This  is  a  white,  yel- 
lowish, or  reddish  friable  sandstone,  wliich  attains  a  thick- 
ness of  120  feet  in  the  southern  part  of  the  state,  but  else- 
where thins  out  and  disapjiears.  It  has  yielded  no  organic 
remains,  except  fucoidal  markings,  and  is  directly  overlaid 
by  the  Trenton  limestone  group. 

This  is  by  Hall  divided  into  three  parts,  a  lower  division 
of  bulf -colored  dolomite,  al)out  twenty  feet  in  thickness, 
holding  the  fossils  of  the  Birdseye  and  Black  River  lime- 
stones of  New  York ;  a  middle  part,  of  about  100  feet  of 
blue  limestone,  carrying  the  organic  remains  of  the  Trenton 
proper  ;  and  an  upper  part,  the  Galena  limestone — the  Up- 
per Magnesian  limestone  of  Owen — a  porous  dolomite, 
abounding  in  lead  ore,  and  attaining  a  thickness  of  2o0  feet. 
Above  this  are  from  200  to  400  feet  of  thin-bedded  lime- 
stones, shales,  and  clays,  the  rei)resentaiives  of  the  Utica 
and  Loraine  shales  of  the  east,  designated  in  the  west  the 
Cincinnati  group. 

§  276.  The  most  significant  fact  about  the  St.  Peter's  sand- 
stone is  that,  according  to  Hall,  it  is  clearly  separated  alike 
from  the  formations  below  and  above,  the  transition  at 
both  horizons  being  "abrupt  and  without  altei-nation  or 
admixture  of  material."  Irving  has  further  notified  that 
it  fills  up  eroded  hollows  in  the  Lower  Magnesian  limestone, 
(which  is  regarded  as  the  representative  of  the  Calciferous 
sandrock,)  being  abruptly  succeeded  by  the  limestones  of 
the  Trenton  group.  The  St.  Peter's  sandstone  thus  occu- 
pies the  x^osilion  of  the  Chazy  formation,  which,  as  has  been 
already  set  forth,  (§  242,  243,)  shows  in  the  eastern  region 
a  break  both  paleontological  and  stratigraphical,  alike  at  its 
base  and  its  summit,  and  in  the  Ottawa  basin  is  in  part  a 
detrital  rock.  This  intermediate  sandstone  in  Wisconsin 
was  consequently  designated  by  Hall  as  the  Chazy  sand- 
stone, (Geol.  of  Wisconsin,  18G2 ;  Irving,  Anier.  Jour. 
Science,  [L^'  vol.  IX,  page  440.) 

§  277.  It  ^as  in  the  lower  sandstones  of  Wisc^onsin,  Min- 
nesota, and  Iowa,  tliat  D.  D.  Owen  discovered  the  remarka- 
ble triK)bitic  fauna,  associated  with  numerous  brachiopods 
and  with  fragments  of  crinoidal  stems,  whicliwas  described 


CAMBRIAN   OF   THE    MISSISSIPPI   VALLEY.        E.    143 


111- 

ka- 

led 


by  him  in  1852.  Hal),  who  reexamined  the  strata  and  re- 
vised the  fauna  in  186^,  distinguished  three  paleontological 
stages.  Of  these,  the  lower  affords  only  Conocoryphe,  with 
Theca  and  some  linguloid  shells.  The  middle  stage  con- 
tains Arlonellus,  Agnosius,  Flijchaspis,  certain  species  of 
Dikellocephalus^  and  of  Conocoryj)he,  to  which  Hall  referred 
some  forms  hitherto  included  in  the  preceding  genus.  With 
this  middle  stage  is  also  found  a  grai)tolite,  Dendrograptus 
Halllanus.  The  third  or  upper  stfige,  declared  by  Hall  to 
be  clearly  separated  from  the  last,  and  from  400  to  500  feet 
above  the  lower  stage,  affords  no  species  of  Conocoryphe, 
but  is  marked  by  the  large  and  characteristic  species  of  Dikrl- 
locephalus,  D.Minnesotensls^  and  D.  Peprnensis,  described 
as  passing  up  into  the  Lower  Magnesian  limestone,  (Ifith 
Appendix  to  Regents'  Report,  180:j,  pages  120,  183.)  This 
third  stage  is  believed  by  Irving  to  correspond  to  the  Men- 
dota  limestone. 

§  278.  This  series  of  about  1,000  feet  of  sedimentary  strata 
below  the  St.  Peter's  or  Chazy  sandstone  of  Wisconsin,  is 
thus  shown  by  the  studies  of  Hall,  to  include  in  its  several 
faunas  representatives  of  genera  of  trilol)ites  found  in  both 
the  Lower  and  Upper  Cambrian  of  Great  Britain,  and  in 
those  sub-divisions  of  the  ILidson-River  group  or  Upper 
Taconic  to  which  the  names  of  Lower  Potsdam  and  Levis 
have  been  given.  The  corresponding  series  of  strata,  con- 
sisting of  alternations  of  sandstone  and  magnesian  lime- 
stone, attains  a  still  greater  thickness  in  Missouri.  TIk- 
Artesian  well  at  St.  Louis  passed  through  2,480  feet  of  such 
strata  between  the  base  of  tlie  Trenton  and  the  lloor  of 
crystalline  granitoid  rocks  beneath.  That  the  tyijical  Pots- 
dam sandstone  of  northei'u  New  York  and  central  ('anada, 
with  its  few  organic  remains,  is  represented  somewhere  in 
the  western  series,  cannot  be  doubted,  but  until  its  fauna 
is  better  knoAvn,  it  will  not  be  possibl*-  to  fix  its  precise 
horizon.  It  will  probably  be  found  desirable,  on  further 
study,  to  revise  the  nomenclature  oii  these  lowest  paleo- 
zoic rocks  in  Americja,  and  to  establish  new  sub-divisions, 
as  in  Europe. 

§  271).   In  conformity  with  the  genenil  principle  regulating 


144  E.      SPECIAL   REPOllT.      T.  STEUKY  HUNT,  1875. 


the:  distribution  of  sediments  over  the  great  American  paleo- 
zoic basin,  we  iind  little  or  nothing  in  tlie  silicious  and  dolo- 
mitic  Cambi'ian  strata  of  the  Mississippi  valley  resembling 
the  Ui)per  Taconic  conglomerates,  sandstojies  and  aigillites 
of  the  eastern  border  of  the  basin.  It  is  proper,  in  this  con- 
nection, to  call  attention  to  some  important  j^oints  in  the 
history  of  tliese  latter  rocks,  and  their  relation  to  the  Silnro- 
Cambrian  strata,  which  have  been  omitted  in  the  preceding 
cha])t('rs,  tliongh  referred  to  in  a  foot-note  on  page  127. 

§  280.  In  the  lirst  annual  report  on  the  geology  of  the 
central  district  of  New  York,  the  strata  al)ove  the  Calcifer- 
ons  san(h'()ck  were  described  by  Conrad  as  consisting  of 
the  fossil  if  erous  limestones  of  Trenton  F,,Ils,  overlaid  by 
dark  shales,  to  which  sncceed  a  series  of  fossil iferons  lead- 
colored  shales,  alternating  with  gray  sandstones,  well  dis- 
j)layed  at  and  near  Pulaski,  (m  tlie  Salmon  l?iver,  in  Oswe- 
go county.  At  the  summit  oi'  these  was  a  bed  of  sandst(me 
quarried  for  grindstones,  and  in  Oneida  county  the  series 
was  overlaid  by  a  qnart/.ose  conglomerate.  Vjinuxem,  \vho 
succeeded  Conrad  in  the  examination  of  the  distiict  the 
next  year,  gave  to  the  Salmon  lliver  strata  the  name  of  the 
Pulaski  shales  and  sandstones.  These  coirespond  to  the 
Loraiue  shales,  (named  from  Loraine,  in  Jefferson  county,) 
and  the  Gray  sandstone  of  Emmons,  which  were  then  sui> 
posed  by  the  latter  to  be  the  equivalents  of  the  Argillite 
and  Oraywacke  series  described  by  Mather,  in  his  fourth 
annual  report  on  the  southern  district  of  New  York,  by  the 
names  of  the  Hudson  slate  group,  or  the  Hudson  Rive^' 
slates,  (§  02,  04.)  The  counties  of  Jefferson  and  Lewis,  in 
(he  northern  dlstri<'t  examined  by  Emmons,  were  connected 
with  tlu;  Hudson  valley  through  the  central  district,  which 
eml)i'aced  the  counties  of  Oswego,  Oneida,  Herkimer,  and 
Montgomery,  extending  southeastward  along  the  Mohawk 
valley. 

^  2S1.  The  rocks  of  this  distiict  were  now  described  by 
A'anuxem,  under  the  name  of  the  Hudson-River  group,  and 
according  to  him,  included  two  entirely  distinct  divisions, 
the  u])])*'!' a  liighly  fossiliferous  series,  the  Pulaski  shales 
and  sandstones,  found  west  of  the  Adirondacks  in  Jefferson, 


J 


VANUXEM   OX   THE   IIUDSON-Iil VEll  GliOUP.      E.    140 


tlie 

Lv,) 

ip- 

ite 

nth 

tlie 

ive^' 

in 

•ted 

licli 

iiid 

i>y 

Illd 

ins, 
lies 
on. 


Lewis  and  Oswego  counties,  and  disappearing-  to  the  soutli- 
eastwai'd  in  Oneida  county.  These  are  the  lead-coh)i'e(l 
shales  and  sandstones  of  Conrad.  The  h>wer  member  of  the 
Hudson  lliver  group,  as  deiined  by  Yanuxem,  was  nanu^l 
tlie  Fra'nlvfort  division,  from  Fraidvfort,  in  Herkimer  coun- 
ty, and  was  described  as  consisting  of  greenish  aigillites 
and  sandstones,  which  underlie  the  Pulaski  shales  to  the 
noitliwest,  as  far  as  Jelferson  county, constitute  in  Ilerkimei" 
and  Montgomeiy  the  only  rei)resentative  of  the  Hudson- 
River  group,  and  extend  eastward,  through  Schenectady, 
Alban}',  and  Saratoga  counties,  to  the  Hudson  river.  Tins 
lower  division  was  said  to  yield  none  of  the  organic  renuiins 
of  the  Pulaski  division,  ))Ut  to  include  some  grai)tolitic 
shales.  To  the  Frankfort  slates  and  sandstoniis,  it  was 
suggested  by  Yanuxem,  might  belong  the  thick  nnisses  of 
argillaceous  strata  of  "controverted  age,"  (the  Tacojuc  of 
Emmons)  along  the  Hudson  valley. 

J$  282.  Yanuxem,  while  he  thus  attempted  to  connect  the 
argillaceous  strata  of  the  northwestern  counties  with  those 
of  the  Hudson  valley,  spoke  of  "  the  diiliculty  of  separating 
or  distinguishing  the  slaty  or  schistose  members  of  the  (Hud- 
son River)  group  from  those  of  greater  age,  with  wiiich  on 
their  eastern  border  the  two  {■sic)  are,  more  or  less,  n-ally  or 
ai)[)arently  blended."  The  force  of  this  observation  is  more 
clearly  apparent  to-day,  when  it  is  known  that  thelaiger2)art 
of  these  schistose  rocks  of  the  Huds(m  River  valley  are 
of  much  great<'r  antiquity  than  the  Pulaski,  (Loraine)  and 
Ftica  slates,  and  must  be  assigned  a  jiosition  below  instead 
of  above  the  Trenton  limestones. 

A'anuxcm  further  remaiks,  that  tln^  two  divisions  of  the 
Hudson  River  gi'oup,  as  ddiucd  by  him,  exist  separati'ly  in 
Pennsylvania.  The  Pulaski  slates,  having  in  all  respects, 
the  same  characters  as  in  New  York,  are  declared  to  occur 
in  the  Nippenose  valley,  west  of  the  Susquehanna,  while 
the  i'^'ankfort  slates  and  sandstones  a])pear  to  the  east  of 
the  North  Mountain,  in  the  Kittatinny  valley,  and  include 
the  rooting-slates  of  the  Delaware.  These  latter  are  placed 
by  Emnu)ns  at  the  summit  of  the  Lower  Taconic,  but  were 
by  Rogers  included,  with  the  fossiliferous  shales  of  Nix)pe- 
[E.  10] 


'HI 


140   E.       SPECIAL    liEPOUT.       T.  STEUllY   HUNT,  1875. 

nose  and  Kisliacoquillas  valleys,  in  tlie  upper  portion  of  his 
Matinal  division. 

§  283.  It  is  important  to  note  in  this  place,  that,  accord- 
ing to  V^anuxem,  tlie  Oneida  conglomerate,  the  admitted 
representative  of  the  conglomerate  and  sandstone  of  the 
North  Mountain  in  Pennsylvania,  rests  in  Oneida  county. 
New  York,  upon  the  Pulaski  shales,  (sometimes  with  the 
intervention  of  the  Gray  band,  which  was  by  Emmons  united 
with  the  Oneida,)  while  in  Herkimer  county  this  conglom- 
erate overlies  directly  tlie  Frankfort  shales  and  sandstones. 

§  284.  In  connection  with  tlie  disappearance  of  the  Pu- 
laski or  Loraine  shales  to  the  southeastward  in  the  Mohawk 
valley,  we  may  note  the  simihir  disappearance  of  the  Tren- 
ton limestones.  These,  in  Canada,  have  been  found  at  jioints 
as  widely  remote  as  Quebec,  Montreal,  Ottawa,  the  Bay  of 
Quintd,  Lake  Simcoe,  and  the  shores  of  Lake  Huron,  to 
have  a  thickness  of  from  600  to  7o0  feet,  being  everywhere 
followed  by  the  Utioii  slates  and  Loraine  shales,  with  a  united 
volume  of  fi'om  800  to  1,100  feet  or  more.  The  thickness  of 
the  Trenton  limestones  in  the  northern  part  of  Lewis  coun- 
ty. New  York,  is,  however,  but  800  feet.  This  is  reduced 
to  100  feet  at  Trenton  Falls,  and  to  thirty  feet  in  the  Mo- 
hawk valley,  while  south  of  the  Mohawk  the  limestone  is 
seldom  over  ten  fee*",  and,  according  to  Conrad,  thins  out 
and  wholly  disappears  to  the  southeast.  He  tdso  notes  that 
the  gray  sparry  fossiliferous  beds,  which,  in  Oneida  county, 
he  distinguislied  as  a  separate  and  lower  division  of  the 
Trenton  group,  grow  thin,  and  disai)pear  to  the  eastward 
along  the  line  of  the  canal,  in  Montgomery  county. 

I^'or  the  statements  in  the  preceeding  sections,  beginning 
with  §  280,  see  the  Geology  of  the  Third  District  of  New 
York,  and  also  the  previous  annual  reports  of  Conrad  and 
Vanuxem  on  the  district,  passim.  The  facts  should  be  con- 
sidered in  comiection  with  the  statements  in  §  245  with  regard 
to  the  relations  of  the  Trenton  audits  overlying  argillaceous 
strata  to  inferior  rocks,  with  those  of  Emmons  in  ,^  07,  98,  and 
with  the  earlier  statements  of  Eaton,  cited  in  §  50.  We  shall 
return  to  the  consideration  of  the  questions  here  raised  in  a 
subsequent  chapter. 


CHAPTER  V. 


niSTOKICAL  SKETCH   CONTINUED. 


US 

(I 

lU 
a 


§  284.  We  have  in  chapters  II  and  III  discussed  tlie  his- 
tory of  the  crystalline  stratified  rocks  of  eastern  North 
America,  up  to  the  year  1855,  at  which  date  the  names  of 
Laurentian  and  Huronian  had  already  been  applied  to  two 
divisions  of  these  rocks  (§  144),  which  had  been  described  and 
defined  by  the  geological  survey  of  Canada  as  more  an- 
cient than  the  base  of  the  Xew  York  paleozoic  series.  Tli  j 
officers  of  that  survey  Jiad  then  adopted,  so  far  as  regards 
the  crystalline  strata  of  the  Atlantic  belt  (with  the  excep- 
tion of  the  Laurentian)  the  view  held  by  Mather,  that  these 
rocks  were  the  altered  equivalents  of  the  Champlain  divis- 
ion of  that  series,  and  consequently  more  recent  than  the 
Laurentian  or  the  Huronian  (§  lGO-174).  We  shall  now 
proceed  to  discuss  successively  the  progress  since  made  in 
our  knowledge  of  the  Laurentian  and  its  divisions,  of  the 
newer  crystalline  schists  of  the  Atlantic  belt,  and  of  the  Vol- 
canic formations  around  Lake  Supeiior  (§  137). 


148   E.      SPECIAL   KKPOHT.      T.  STERRY   HUNT,  1875. 


iii 


§  285.  The  so-called  Metanioiphic  pjneissic  series  to  which, 
in  1854,  the  name  of  Laurentian  was  given  had,  as  already 
shown,  been  l)y  Logan,  from  his  observations  on  the  Ottawa 
river  in  1845,  divided  into  two  groups,  the  upper  one, 
with  its  intercalated  bands  of  crystalline  limestone,  being 
regarded  as  a  sei)arate  overlying  formation  ;  (§  13;];  a  distin(;- 
tion  which  is  well  founded,  but  has  generally  been  disre- 
garded in  subsequent  descriptions  of  these  rocks.  In  1847 
the  present  writer  spent  some  time  in  the  examination  of 
the  crystalline  limestones  of  this  series,  and  their  associated 
rocks,  as  seen  at  various  localities  along  the  vjdley  of  the 
Ottawa,  as  far  as  Poi-tagc;  du  Fort,  and  in  the  vicinity  of 
Perth,  Ontario.  The  observations  then  made  were  given  in 
the  report  of  the  survey  of  1847,  (pages  125-138)  and  the 
results  of  chemical  analyses  of  the  materials  collected  at 
that  time,  in  the  report  of  1850  (pages  35-46). 

§  286.  In  1850,  Mr.  Alexander  Murray,  in  company  with 
the  writer,  examined  these  same  rocks  to  the  north  of  the 
Thousand  Islands.  The  observations  then  made  will  be 
found  in  Murray's  report  of  1851  (pages  59-04).  The  most 
important  fact  there  announced  was  the  occurrence  of  a  bed 
of  silicious  conglomerate,  found  in  the  township  of  Bastard, 
intercalated  in  the  crystalline  I'mestones  of  the  series,  which 
here  dip  N.  55°  E.  <  30°.  The  limestone  layers,  both 
above  and  below,  are  white,  coarsely  crystalline,  graphitic 
and  micaceous,  while  the  overlying  one  contains  clion- 
drodite.  The  included  conglomerate  layer,  eighteen  inches 
in  thickness,  is  a  finely  granular  sandstone,  including  large 
and  small  well-defined  pebbles  of  vitreous  quartz,  and  others 
which  could  only  be  described  as  a  laminated  sandstone. 
Pebbles  and  rounded  grains  of  feldspar,  together  with  scales 
of  mica  and  of  graphite  were  also  found  in  the  matrix.  It 
is  not  imjirobable  that  this  .'uique  occurrence  may  be  due 
to  a  dislocation,  followed  by  movements  of  the  strata,  l)y 
which  a  more  recent  conglomerate  has  become  enclosed  in 
the  ancient  limestones. 

§  287.  It  was  not  until  1853  and  1854,  that  the  difficult 
task  of  unraveling  the  structure  of  these  ancient  rocks 
was  undertaken  by  Logan.     The  first  results  of  his  labors 


HISTORY    OF   LABUADOUITE    ROCKS. 


E.   149 


lult 

lors 


therein  were  set  forth  in  the  little  essay  called  an  Esquisse 
Geologique  diu  Canada^  published  at  Paris  in  ISOa  (?}  144), 
but  f  urf  lier  researches  were  made  by  him  in  ISfM),  and  his  con- 
clusions are  given  with  some  detail  in  tlie  report  for  isr^lj-nc, 
(pages  7-52)  published  in  1857 ; — which  wasacconii)anied  by 
a  map  showing  the  geographical  distribution  of  the  Lauren- 
tian  limestones  in  the  counties  of  Argenteuil  and  Terrebonne, 
a  little  north  and  west  of  Montreal.  In  this  report  was 
shown  the  existence  of  one  or  more  great  bands  of  crystal- 
line limestone,  interstratilied  with  the  gneisses  and  accom- 
panied by  considerable  masses  of  quartzite  and  of  mag- 
netite, tlie  whole  being  greatly  folded,  and  intersected  by 
numerous  masses  of  eruptive  rocks. 

§  288.  The  rock  already  recognized  by  Emmons  under  the 
name  of  hypersthene-rock  or  labradorite-rock,  in  tlie  Adi- 
rondacks  (§  88)  was  also  found  in  the  region  in  question. 
Rolled  masses  of  it  liad  long  been  known  in  the  valley  of 
the  St.  Lawrence,  and  the  rock  had  been  observed  in  place 
by  Dr.  Bigsby,  on  the  northeast  shore  of  Lake  Huron,  where 
it  was  described  as  occupying  a  breadth  of  live  miles. 
(Amer.  Jour.  Science,  I,  viii,  GO).  In  1852  Logan  found  a 
considerable  area  of  the  rock  in  Mille-Isles,  Morin  and 
Abercrombie,  in  the  county  of  Terrebonne,  and  a  speci- 
men of  it  was  described  by  the  writer  in  some  detail,  with 
analyses,  in  the  report  for  1852,  (page  107)  and  shown  to 
consist  of  cleavable  lavender-blue  labradorite,  in  a  greenish 
base  composed  chietly  of  the  same  feldspar  with  4.8  per 
cent,  of  carbonate  of  lime  and  a  little  magnetite. 

§  289.  In  the  following  year  the  writer  examined  the  rocks 
of  this  region  in  company  with  Logan,  and  subsequently 
extended  his  observations  to  several  other  points.  The  first 
results  of  these  examinations  are  given  in  Logan's  report  for 
1853-5G  (pau'es  35-37,)  and  inasmuch  as  the  rocks  in  ques- 
tion have  since  assumed  a  considerable  geological  import- 
ance it  is  thought  best  to  rei)rint  therefrom  the  following 
extracts,  defining  their  lithological  characters.  (§  132.) 

§  290.  The  rocks  are  described  in  general  terms  as  "chiefly 
compos  "■  of  lime-feldspar,  varying  in  composition  between 
labradorite  iind  andesine,  and  are  marked  by  the  presence 


150  E.      SPECIAL   REPORT.      T.    STERRY   HUNT,    1875. 


■;  I 


m 


HI! 


of  hypersthene  and  iliiienite."  Of  one  locality  .idjoining 
the  crystalline  limestone  in  Mille-Lsles  it  was  said,  "  the  rock 
is  chieHy  labnidoritc,  and  consists  of  a  tine-grained  paste 
of  tliis  mineral,  of  a  puri)lish-grey,  weathering  to  an  opaque 
white,  and  holding  cleavable  forms  of  a  lavender-blue  feld- 
spar, several  inches  in  diameter.  Many  of  these  exhil)it 
a  fine  golden-green  and  deej)  blue  opalescence,  and  the  same 
hues  occasionally  emanate  from  minute  j^oints  in  the  paste. 
The  rock  is  generally  massive,  and  it  is  occasionally  very 
difficult  to  find  any  indication  of  those  parallel  planes  which 
are  so  generally  present  in  common  gneiss.  The  large  cleav- 
able  forms  of  labradorite,  however,  as  well  as  the  hyper- 
sthene and  ilmenite,  are  found  to  prevail  in  belts  that  ap- 
pear to  be  parallel  to  one  anothei',  and  garnetifei-ous  or  mi- 
caceous l)ands  occasionally  indicate  the  same  arrangement." 

§  291.  At  St.  Jerome,  on  the  east  side  of  Rividrt}  du  Nord, 
a  rock  belonging  to  the  same  area  as  that  last  mentioned 
was  described  as  gneissic  in  structure.  "  Darkei'  and  lighter 
bands  run  parallel  to  one  another,  the  shades  being  occa- 
sioned by  the  greater  or  less  abundance  of  a  line-grained 
greenish  lime-feldspar,  weathering  ojjaque  white,  which  oc- 
curs in  spots,  surrounded  by  a  darker  colored  network, 
consisting  of  a  dark  green  pyroxene  and  magnetic  iron  ore, 
with  small  disseminated  clusters  of  yellowish-red  garnets. 
In  this  mass,  large  and  small  individuals  of  labradorite, 
some  of  them  two  or  three  inches  in  diameter,  are  irregu- 
larly disseminated,  and  irregular  veins  or  apjiarent  segre- 
gations occur  here  and  there,  composed  of  flesh-red  oitho- 
clase  and  translucent  colorless  quartz." 

§  292.  "On  the  west  side  of  the  river,  rock  of  a  similar 
character  is  met  with,  but  there  is  seen  also  an  interstratified 
mass  of  reddish  hornblendic  gneiss,  the  feldspar  of  which 
is  orthoclase.  The  breadth  of  the  mass  of  gneiss  is  two  hun- 
dred yards,  and  it  is  marked  by  beds  darker  than  other 
parts  from  the  presence  of  hornblende.  *  *  On  the 
west  side  of  this  mass  of  gneiss  smaller  bands  of  a  similar 
nature  seemed  to  alternate  with  those  containing  lime-feld- 
spar. Beds  of  quartz  were  also  interstratitied.  and  some  of 
these  were  in  one  place  so  loaded  with  small  garnets  as  to 


■■«!' 


HISTOIIY    OF    LABKADORITE    ROCKS. 


E.  151 


lar 

5ed 

ch 

11  n- 

lier 

Ihe 

ar 

d- 

of 

Ito 


form  a  fine  granular  garnet-rook.  '■•  *  LiniH-fcldsparrock, 
more  resembling  that  of  Monn  in  its  opaque  white  massive 
asjiert,  was  mot  with  at  New  (Jlasgow,  on  tho  Aohigan,  in 
Terrebonne  seigniory;  tho  stratiliration,  howevor,  was  well 
marked  by  bands  of  garnets  and  pyroxono,  and  by  alter- 
nations of  the  rock,  on  the  west  side,  with  common  gneiss." 
Similar  rocks,  belonging  to  the  same  area,  were  examined 
further  to  the  northeast  in  Rawdon,  and  in  Chertsey,  in  the 
county  of  Leinster. 

^  2!):?.  Th(>  materials  collected  in  the  localities  above  men- 
tioned, and  also  in  another  area,  in  Chateau  llichor  in  the 
county  of  Montmorenci,  were  subsequently  submitted  to  a 
chemical  and  lithological  examination  by  the  writer,  and 
described  in  the  report  for  1853-50  (pages  373-i3S;3)  as 
belonging  to  crystalline  strata  closely  associated  with  the 
limestones,  gneisses  and  quartzites  of  the  Laurentian  series. 
Of  tho  rocks  in  question  it  was  said  :  "  They  are  comi)osed 
chiefly  of  feldspar,  with  small  portions  of  black  mica,  green 
pyroxene,  and  occasionally  epidote,  garnet  and  quartz  ;  i)or- 
tions  of  hypersthene  are  also  frequently  present,  and  hence 
the  New  York  geologists  have  designated  these  essentially 
feldspathic  strata  by  tho  name  of  hyporsthene-rock.  In 
addition  to  the  minerals  just  mentioned,  we  may  add  ilnion- 
ite  or  titaniferous  iron,  which  occurs  sometimes  in  large 
masses,  and  at  other  times  in  small  disseminated  grains, 
which,  like  the  hypersthene,  appear  to  mark  the  planes  of 
stratilication.  If  to  these  we  add  small  portions  of  iron  i)y- 
rites,  and  a  little  disseminated  carlxmate  of  lime,  we  shall 
have  the  mineralogy  of  these  rocks,  so  far  as  yet  known." 

"The  texture  of  these  feldspar  rocks  is  varied  ;  sometimes 
the  mass  is  a  confusedly  crystalline  aggregate,  exhibiting 
cleavage-surfaces  three  or  four  inches  in  diameter,  with  a 
finegrained  somewhat  calcareous  jwste  in  the  interstices. 
Sometimes  the  whole  rock  is  uniformlj''  granular,  whih?  more 
frequently  a  granular  base  holds,  at  intervals,  cleavable 
masses  of  feldspar,  often  several  inches  in  diameter.  The 
colors  of  these  rocks  vai-y  from  grayish  and  bluish- white, 
to  lavender  and  violet-blue;  flesh-red,  greenish  and  bi'own- 
ish  tints  are  also  met  with ;  the  colors  are  rarely  brilliant. 


152  E.      SPIOCIAL   KEPOKT.      T.  STKRRY   HUNT,  1875. 


These  feldspars  seldom  occur  in  distinct  crystals,  but  their 
cleavage  is  triclinic,  a  fact  which  taken  in  conn(?ction  with 
the  densities,  varying  from  2.00  to  2.73,  shows  them  to  be- 
long to  the  group  of  which  albite  and  ancn'thite  may  l)o  taken 
as  the  rejiresentatives.  The  bluish  cleavable  varieties  often 
exhibit  the  opalesence  of  labradorite,  to  which  species 
American  mineralogists  have  hitherto  referred  them  ;  but 
with  th(i  exception  of  a  few  analyses  by  myself,  we  have 
had  as  yet  no  published  chemical  examinations  of  any  of 
these  feldspars.  My  investigations  show  that  while  all  of 
them  are  feldspars  with  a  base  of  lime  and  soda,  the  com- 
position varies  very  much,  being  sometimes  that  of  labra- 
dorite, andesine,  or  intermediute  varieties,  and  at  other 
times  approaching  to  that  of  anorthite." 

§  294.  Of  the  lime-feldspar  rocks  of  the  county  of  Lein- 
ster  it  was  then  said :  "In  tiie  townships  of  Rawdon  and 
Chertsey,  they  are  often  fine-grained  and  homogeneous,  and 
constitute  an  exceedingly  tough  I'ock,  with  an  uneven  sub- 
conchoidal  fi'actur(%  and  a  l'eel)ly  vitreous  lustre  ;  this  va- 
riety is  bluish  or  grayish-white  in  color,  somewhat  translu- 
cent, and  exliil)its  here  and  there  the  cleavage  of  grains  of 
feldspar.  Great  masses  of  this  rock  are  almost  free  from 
foreign  minerals,  while  other  portions  abound  in  a  green 
granular  pyroxene,  arranged  in  thin,  interrupted  i)arallel 
layers,  with  ilmenite.  These  layers  of  pyroxene  are  seldom 
more  than  four  or  live  lines  in  thickness,  and  occur  an  inch 
or  two  apart,  while  the  layers  of  the  ilmenite  are  still  thin- 
ner, and  often  enclosed  in  those  of  the  pyroxene,  idcmg  the 
limits  of  which  deep-red  grains  of  garnet  are  occasionally 
seen.  These  different  minerals  appear  in  lelief  on  the  white 
weathered  surface  of  the  rock,  and  give  a  picture  of  its 
stratified  structure,  which  however  is  not  less  apparent  on 
the  surfaces  of  recent  fracture.  Small  rounded  l)luish 
masses  of  cleavabh^  feldspar  are  frecxueiifly  diss'ininated 
in  the  same  planes  as  the  other  minerals.  1-.  some  in- 
stances the  pyroxene  appears  to  graduate  into,  and  to  be 
rei>laced  liy,  foliated  hypersthene." 

^  29j.  Of  the  i  ime-feldspar  rocks  of  Chateau  Richer,  it  was 
said  :     "  They  cover  a  breadth  of  two  or  three  miles  across 


S  «f' 


nibiORY   OF   LABUADOUITE   ROCKS, 


E.  153 


the  strike,  bounded  by  crystalline  limestone  on  one  side, 
and  a  qnartzo-feldspatlii(^  rock  on  the  other,  and  risin-j;  into 
small  hills.  In  this  area  there  oeciir  several  varieties  of  the 
rock,  but  the  most  interestinij;  is  the  one  made  up  of  a  line 
granular  base,  greenish  or  grayish-white  in  color,  holding 
masses  of  a  reddish  cleavable  feldspar,  wliich  are  sometimes 
from  one  tenth  to  one  half  an  inch  in  diameter,  but  often 
take  the  form  of  large  imperfect  crystals,  frequently  twelve 
inches  long  and  four  or  live  inches  wide.  These  dimen- 
sions correspond  to  the  faces  M  and  T,  while  the  face  P, 
characteriztnl  ])y  its  jierfect  cleavage,  is  from  half  an  inch  to 
tw^o  inclies  broad.  Twin  crystals  sometimes  occur,  having 
a  composition  parallel  to  M," 

"Ilypersthene  is  met  with  throughout  the  rock  in  flat- 
tened masses,  which,  although  variable  and  irregular  in 
their  disfribution,  exhibit  a  general  parallelism ;  they  are 
occasionally  four  or  five  inches  in  breadth,  by  an  inch  or 
more  in  tliickness,  and  are  separated  fnuu  thegranulai-  I'elds- 
patliic  base  by  a  thin  lilm  c;f  bi'ownish-black  mica.  Titan- 
iferous  iron  ore  is  also  found  in  the  rock  in  grains  and  len- 
ticular masses,  occasionally  an  inch  or  two  in  thickness ; 
these  occur  in  the  granular  base,  and  generally  near  the  hy- 
persthene,  but  grains  of  the  ore  are  occasionally  found  in 
the  crystalline  feldsjvir.  [which  is  andesine].  Quartz,  in 
small  grains,  is  imbedded  in  the  titaniferous  iron  ore,  but 
was  not  observed  elsewhere  in  the  rock." 

§  2DG.  The  report  already  cited  gave  fourteen  analyses  of 
of  these  feldspathic  rocks,  including  both  the  cleavable 
feldspars  and  the  surrounding  paste,  and  showing  a  varia- 
tion in  the  amount  of  silica  from  47.40  to  59.80  percent., 
and  in  the  lime  from  7.73  to  14. "Jt  per  cent.,  thie  propoi'tion 
of  alkaM  (chic^tly  soda)  generally  decreasing  as  that  ol'  the 
lime  augmented  ;  v.  Idle  the  specill(^  gravity  varied  from  2A)7 
to  2.7.'?.  The  analyses  of  all  these  feldsi)ars,  as  W(dl  of  the 
accompanying  hypersthene  and  ilmenite,  will  be  found 
under  their  respective  heads  in  th(i  Geology  of  Canada, 
where,  on  page  590,  is  given  the  mean  composition  of  the 
felds])ars,  as  d<'du<'ed  from  many  analyses.  For  the  views 
at  that  time  put  forth  as  to  the  constitution  of  these  feld- 


fi! 

■i 


IM   E.       SPECIAL    REPORT.      T.  STKP.RY    JUJNT,   1875. 


til 


I; 


i 


;:i 


M! 


sjuirs,  the  reader  is  referred  to  the  uiithor's  paper  in  the  L. 
E.  and  D.  Pliilosophical  Magazine  for  May,  ISi'iS,  and  to  his 
Chemical  and  Geological  Essays,  page  448. 

§  297.  The  report  of  the  surrey  for  JC58  (publislied  in 
1859)  contains  the  results  of  further  explorations  by  Sir 
William  Logan,  and  his  assistant  Mr.  James  Lowe,  in  the 
Laurentian  region  already  referred  to,  northwest  of  Mon- 
treal, during  the  years  1857  and  1858.  An  attempt  was 
therein  made  to  fix  the  succession  and  thickness  of  the 
gneissic  and  limestone  series,  and  the  conclusions  then 
anncmnced  were  confirmed  by  the  labors  of  the  following 
three  years.  The  ''Geology  of  Canada,'"  a  volume  of  983 
pages  octavo,  published  in  18013,  was  in  great  part  printed 
in  18G2,  and  the  first  twenty  chapters  rej)resented  the  state 
of  our  knowledge  of  the  rocks  in  question  at  the  close  of 
18(51.  Chapter  XXII  however  gave  the  fui'ther  results  of 
the  field-work  of  18(52.  This  volume  was  accompanied  by 
an  Atlas  with  exphuiatory  text,  which  contained  a  colored 
geological  map,  showing  the  distribution  of  the  Laurentian 
limestones  in  the  counties  of  Ottawa.  Terrebonne,  Argen- 
teuil  and  Two-Mountains.  The  breadth  of  the  region  thus 
mapped  (on  a  scale  of  seven  miles  to  the  incli)  was  about 
fifty  miles  from  east  to  west,  and  its  greatest  length  about 
the  same.  The  sharply  folded,  and  ofter  inverted  strata 
have  a  strike  about  ten  degrees  east  of  north. 

§  208.  The  succession  in  this  region,  as  now  described  by 
Logan,  was  as  follows  in  ascending-  order  from  a  great 
underlying  m.ass  of  gneiss,  which  niaives  the  Trembling 
Mountain  in  Grandison,  and  is  <h^signatt'd  in  the  geological 
map  already  referred  to  as 


o 


A.  First  Orthoclase  Gneiss;  Uiiclcnoss  unl<t><)wn. 

B.  I'irst  or  Troinl)ling-Lako  Limestone  band.  .   .   .   1,500  foot. 

C.  Sooond  Orthocliiso  Otiol.ss 4,000  foot. 


D.  Second  or  fJroor-Lalio  Limostono  band,  includ- 
ing t...  subnrdiiijitc  l);iii!l.s  dT  garnotiibroiis 
qiiartKitc;  and  liornbh'ndic  gi:ois.s,  nialvinff  up 
aljont  one  lialftlio  volume 2,500  feet. 


DIVISIONS   IN  THE   LAURENTIAN   SERIES.         E.  155 

E.  Third     Orthoclaso    GnoLss — including     several 

bands  of  garnetiferous  gneiss  and  quurtzito  in 
tlio  lower,  and  nnicli  coarsely  porphyrltic 
gneiss  in  the  upper  part 3,500  feet. 

F.  Third  or  Grenville  Limestone  band,  said  to  vary 

in  thiclcncss  from  00  to  l,r)00  feet,  luiving  in 
some  parts  an  interstratified  band  of  gneiss, 
and  estimated  at 750  feet. 

G.  Fourth  Orthoclaso  Gneiss  including,  besides  a 

tliin  l)ed  of  limestone,  a  band  of  fiOO  feet  of 
quartzite 5,000  feet. 

17,1250  feet. 


§  299.  The  collective  ime  of  the  Grenville  series  was 
subsequently  applied  to  the  whole  succession  from  the 
base  of  the  limestone  B.  to  the  summit  of  the  gneiss  G. 
(Geology  of  Canada,  page  839).  This  corresponds  to  the 
upper  group  in  the  Laurentian  series,  originally  indicated 
by  Logan  in  1845,  (§  133)  while  the  great  underlying  mass 
of  granitoid  gneiss,  A.,  of  unknown  thickness,  which  is 
largely  developed  in  the  county  of  Ottawa,  and  may  be 
called  the  Ottawa  Gneiss,  is  the  lower  group. 

§  300.  The  name  of  orthoclase-gneiss  was  used  to  desig- 
nate the  feldspathic  rocks  of  the  Ottawa  and  Grenville  divis- 
ions, becaus('  the  feldspar  belongs  chielly  to  the  species 
orthoclase,  although,  as  was  then  pointed  out :  "Small  por- 
tions of  a  white  triclinic  feldspar,  which  is  api3arently  olig- 
oclase  or  albite,  are  occasionally  found  with  the  reddish 
orthoclase  of  the  coarser  gneiss."  It  was  further  shown, 
however,  that  a  tine-grained  reddish  gneiss  from  Grenville, 
in  which  orthoclase  was  apparently  the  predominant  min- 
eral, contained  nearly  as  much  soda  as  i)otash  (Ibid,  587). 

To  distinguish  from  these  qiiart/o-feldspatljic  rocks  the 
more  basic  gneissoid  roi^ks,  consisting  cliieliy  of  lime-l'eld- 
spars.  anorthic  in  crystallization,  (for  which  Delesse  liad 
])i'oposed  the  general  term  of  anorthose)  the  name  of 
anorthosite  rocks,  or  anortholites,  was  at  this  time  suggest<'d 
for  the  latter  . 

§  301 .   It  was  then  the  opinion  of  the  present  writer,  as  ex- 


16G  E.      SPECIAL   REPORT.      T.    STEKllY   HUNT,  1S75. 


^wH! 


pressed  in  ISGl,  that  "future  investigations  may  furnish  evi- 
dence which  will  divide  the  Laurentian  series  into  several 
formations,  distinguished  by  want  of  conformity  and  by 
mineralogical  diiferences."  (Ibid,  page  580).  This  exx)ecta- 
tion  was  soon  fulfilled.  In  chapter  III  of  the  GeoL^gy,  from 
which  the  above  section  is  condensed,  a  fourth  limestone 
^"^d,  that  of  Morin,  is  mentioned  as  probably  occupying  a 
position  above  the  fourth  gneiss,  Gr.,  and  as  followed  by  the 
great  mass  of  anorthosite  rocks  which,  with  a  genei'ally  high 
westward  dip,  occupy  an  area  at  least  twelve  miles  in 
breadth,  to  the  north  and  east  ol"  the  region  mappetl.  To 
tliese  rocks  was  jirovisionally  assigned  a  volume  of  10,000 
feet,  but  it  was  exj^ressly  said  that  "the  thickness  is  wholly 
conjectural." 

§  802.  The  explorations  of  18G2  added  materially  to  our 
knowledge  of  the  relations  of  these  anorthosite  rocks.  Ly- 
ing apart,  and  to  the  west  of  the  great  area  in  the  counties 
of  Terrebonne  and  Leinster,  there  was  discovered  in  Sala- 
berry,  a  smaller  portion  of  anortholite,  beneath  which  one 
of  the  limestone  bands  of  the  Grenville  series  appeared  to 
pass.  It  was  also  found  that  the  Morin  limestone  band, 
(supposed  to  be  a  repetition  of  one  of  those  named  in  the 
section)  disappears  in  like  manner  beneath  the  southwest 
edge  of  the  great  anortholitearcui.  From  these  facts  it  was 
considered  "probable  that  tin?  anorthosite  rock  overlies  the 
whole  Grenville  series  uncouformably,  and  that  the  mass 
of  it  on  the  west  side  of  Sahd)erry  is  an  outlying  portion," 
giving  reason  to  suppose  "the  existence  in  the  Laurentiiin 
system  of  two  immense  sedimentarv  formations,  thf*  one  sup- 
erimposed unconformal)ly  upon  the  other,  witli  probal)ly  a 
great  diireronce  in  lime  betwf^en  them."  In  confirmation 
of  what  had  been  i)reviously  assorted  as  to  its  lithologi- 
cal  character,  it  wa,-!  further  said;  "This  new  formation, 
altho^^gh  characterized  by  a  predonunance  of  anortholites, 
appear  to  contain  in  some  parts  interstratilied  beds  of  ortlio- 
clase-gneiss,  cpiartzites  and  limestones,  all  of  which  are 
found  associated  with  it  near  New  Glasgow"  (Ibid,  pageSIW). 

^ 'AO',].  In  the  originnl  (h'scription,  the  FourHi  Orihoclase 
Gneiss,  G.  of  the  section,  was  s:iid  to  be  intorstratilied  in 


HISTORY    OF   LABRADORITE    ROCKS. 


E.  157 


g-1- 


its  upper  part  with  anortholites  (§  202)  and  was  rpuarded 
as  sliou'ing"  a  passage  from  the  gneisses  below  into  tlie  an- 
ortliolites  above.  Since  however  this  ni)per  series  elsewhere 
includes  layers  of  orthoclase-gneiss  and  quartzite,  not  nn- 
like  those  fonnd  in  the  Grenville  series,  it  is  probable  that 
these  supposed  beds  of  passage  are  refdly  a  portion  of  the 
newer  formation. 

It  was  both  on  acconnt  of  this  association,  and  of  the 
gneiss-like  structure  of  the  anortholites  themselves,  that 
this  overlying  series  way  designated,  alike  in  the  text  of  the 
Atlas,  and  on  the  map  pul)lished  in  ISO."),  by  the  name  of 
Anorthosite  Gneiss.  This  was  then  called  Upper  Lauren- 
tian  or  Labradorian,  the  name  of  Lower  Laurentian  being 
reserved  for  the  gneisses,  quartzites,  and  limestcmes  of  the 
Grenville  series,  and  tlie  underlying  Ottawa  Gneiss. 

§  ;]04.  The  further  liistory  of  these  labradorite  or  anor- 
thosite rocks  may  here  be  told.  Besides  the  localities 
already  mentioned,  near  Montreal  and  near  Quebec,  they  are 
found  at  many  places  within  the  Laurentian  region  (m  the 
north  side  of  the  lower  St.  Lawrence.  They  ai-e  known  in 
the  parish  of  St.  Trbain,  near  Bay  St.  Paul,  jind  over  a 
large  area  on  the  Saguenay,  between  Chicoutiini  and  Lake 
St.  John.  A  description  of  the  labradorite  rocks  of  this 
latter  district,  as  observed  and  collected  by  Mr.  James  Rich- 
ardson in  1857,  will  be  found  in  the  rei')ort  for  that  year 
(pages  79 — 84.)  Many  beautiful  varieties  are  there  met  with, 
and  the  stratification,  which  is  well  marked,  sometimes 
shows  inchided  b:inds  of  orthoclase  gneiss,  and  in  one 
locality  a  layer  of  pak,'  green  i^yrallolite  (renssellaerite.) 
In  some  instances  the  blue  granitoid  labradoi-ite  rock  con- 
tains distinct  grains  of  vitreous  quartz,  which  is  however 
comparatively  rare.  Similar  rocks  are  found  at  many 
points  along  the  north-west  shore  of  the  Gulf  of  St. 
Lawrence,  from  the  Saguenay  as  far  as  Labrador.  Tiiey 
are  well  seen  at  the  mouth  of  the  Pentecost  river,  about 
IGO  miles  below  the  mouth  of  the  Saguenay,  and  on  the 
Bay  of  Seven  Islands,  some  forty  miles  further.  This 
locality  is  probably  connected  with  the  lai-ge  extent  of 
similar  rocks,  observed  by  Prof.  Hind  to  form  a  chain  of 


If 


■  IH 


158   E.      SPECIAL   REPORT.      T.  STEKRY  HUNT,   1875. 


Wii! 


hills  along  the  River  Moisie.  Labradorite  rocks  were  also 
observed  by  Bayfield  to  occupy  the  coast  for  several  miles, 
near  Mingan.  In  each  of  these  localities,  these  rocks  appear 
to  be  in  contact  only  with  the  Laurentian  gneiss,  except  in 
the  area  near  Montreal,  where  their  southern  border  is  un- 
conformably  overlaid  by  the  Potsdam  sandstone  of  the  St. 
Lawrence  valley. 

§  305.  The  rocks  are  widely  spread  on  the  coast  of  Lab- 
rador, wliere  their  characteristic  feldspar  was  first  found, 
and  whence  it  takes  its  name.  Prof.  A.  S.  Packard,  Jr.,  has 
described  some  of  the  localities  in  this  region,  where  he 
found  considerable  areas  of  anortholite  surrounded  by 
gneiss,  and  obsei'ved  bosses  or  domes  of  it  resting  ujion 
stratified  quartzose,  horublendic  and  feldspathic  rocks,  in 
such  a  manner  as  to  lead  him  to  suppose  the  anortholites 
to  be  eruptive,  (Mem.  Bost.  Soc.  Nat.  Hist.  Vol.  I,  part  ii, 
pp.  214-217.)  Labradorite  rocks  were  long  since  observed 
by  Jukes  in  the  western  part  of  Newfoundland,  and  Mr. 
Alex.  Murray,  in  his  geological  map  of  the  island,  pub- 
lished in  1870,  has  shown,  besides  several  smaller  areas,  a 
belt  of  more  th:in  fifty  miles  in  length  of  these  rocks, 
called  by  him  I'pper  Laurentian,  near  St.  George's  Bay. 

§  30G.  The  Ifjalities  of  labradorite  rocks  on  the  coast  be- 
tween the  Sa'j,uenay  and  the  Bay  of  Seven  Islands,  were 
examined  by  Mr.  James  Richardson  in  1800,  and  the  ma- 
terials having  been  submitted  to  the  examination  of  the 
writer,  the  results  are  set  fortli  in  Mr.  Richardson's  report 
for  that  year  (Report  of  Progress  for  lSGG-1800,  page  :3()5). 
The  Laurentian  there  consists  of  coarser  and  finer  reddish 
and  grayish  gneisses,  often  enclosing  liornblendic  and  mi- 
caceous layers,  and  including  great  masses  of  vitreous 
(piartz,  sometimes  pure,  and  at  othor  times  holdingsparingly 
disseminated  plates  of  llesh-i'cd  feldspar.  IVds  of  cryastl- 
line  limestone,  enclosing  green  pyroxene,  are  included  in 
the  gneiss. 

§  307.  The  labradorite  rocks  there  met  with  present  many 
varieties  resembling  those  found  near  Montreal.  Besides 
hypersthene,  they  sometimes  include  nodular  masses  of 
red  garnet,  and  others  of  a  gray  fibrous  hornblende.     Bands 


niSTORY    OF    LABRADOPITE    ROCKS. 


E.   159 


of  anortholites,  coarser  and  finer  in  texture,  and  marked  by 
these  different  minerals,  serve  to  make  very  apparent  the 
stratification,  which  is  extremely  regular,  and  near  Pente- 
cost River  is  seen  in  a  range  of  low  cliffs,  dipping  N".  23°  E, 
<  30°  to  40°.  At  the  Bay  of  Seven  Islands,  in  like  man- 
ner, the  dark  bluish  anortholites,  characterized  by  hyper- 
sthene,  and  includinggreat  masses  of  titanic  iron-ore,  appear 
for  a  distance  of  three  or  four  miles,  with  a  nearly  uniform 
dip  of  from  10°  to  20°  to  the  northward.  The  reddish  Lau- 
rentian  gneiss  is  in  one  place  "seen  to  be  distinctly  over- 
laid by  a  patch,  only  a  feAv  yards  square,  of  labradorite 
rock,  showing  considerable  varieties  in  character,  and  clearly 
stratified." 

§  308.  The  conclusion  from  till  the  ol)servations  along  this 
coast  is  thus  stated  :  For  the  Laurentian  gneiss,  "the strike 
is  generally  nearly  north  and  south,  Avith  di^^s  often  aj)- 
proaching  the  vertical.  The  strata  are  all  more  or  less 
brok(Mi,  contorted  and  faulted.  The  labradorite  rocks  rest 
unconformably  upon  the  Laurentian  ;  they  generally  strike 
nearly  east  and  west,  at  comparatively  moderate  angles, 
with  little  or  no  appearance  of  contortion  or  disturbance." 
Both  the  Laurentian  and  the  labradorite  rocks  are  cut  by 
granitic  veins  containing  red  orthoclase,  greenish  oligoclase, 
black  hornblende,  muscovite,  molybdenite,  and  sometimes 
crystalline  masses  of  magnetite. 

§  309.  At  an  early  date  in  the  history  of  the  investiga- 
tion of  the  Laurentian  its  mineralogical  resemblances  with 
the  Primitive  gneiss  of  Eui'ope  wer(^  evident.  Th(i  writer,  in 
18i)4,  declared  that  bolli  "in  i)ositiou  and  in  lithological 
characters  the  Laurentian  st'iiesaifpcars  to  corres])oad  to  the 
old  gneiss  formation  of  L.ii)land,  Finland  ;ind  Scandinavia," 
(Anier.  Journal  Science  IL  xviii,  19;"),)  and  in  the  I'J.squ/s.se 
Gcolof/iquc,  already  cited,  it  was  added  "to  the  similar 
rocks  of  the  north  [westj  of  Scotland."  In  the  di^scriptiou 
then  given,  the  anortholites  were  as  yet  regarded  as  form- 
ing a  part  of  the  Laurentian,  and  these  rocks,  as  found  in 
Essex  county.  New  York,  had.  we  have  seen,  been  by  Em- 
mons compared  with  the  hy.i)ersthen<^-rock  or  labradorlte- 
rock  found  by  Macculloch  in  the  Western  Islands  of  Suot- 


1#l 


160  E.      SPECIAL   REPORT.      T.  STERUY  HUNT,  1875. 


land.  In  order  to  verify  this  comparison,  the  ■writer,  hav- 
ing- iirst  procured  specimens  of  tlie  rock  from  Loch  Scarvig 
in  the  Isle  of  Slvye,  obtained  access  to  the  collections  made 
in  that  island  by  Macculloch,  and  now  in  the  possession  of 
the  GeoloL!;ical  Society  of  Lon(hjii,  and  convinced  himself 
of  their  close  resemblances  to  the  anortholites  of  New  York 
and  Canada. 

§  310.  Both  Macculloch  and  Emmons  regarded  these  lab- 
i"adorit(;  rocks  are  eruptive,  Gi(di.ie,  in  his  subsequent  ge- 
ological studies  in  Skye,  expressed  the  same  view,  and  ap- 
peared to  confound  Ihem  with  certain  eruptive  greenstones. 
The  writer  s  oljservations  and  conclusions  respecting  these, 
and  theother  crystalline  rocks  of  the  Western  Islands,  were 
set  forth  in  the  Dublin  Quarterly  Journal  for  July,  18G3, 
where  the  stratified  character  of  the  labradorite-rocks  of 
Canada,  and  their  correspond(Mice  with  those  of  Skye  was 
pointed  out.  In  the  following  year  Prof.  Ilaughton,  of  Dub- 
lin, visited  Loch  Scarvig,  in  Skye,  and  in  the  same  Journal 
for  180.")  (i)age  G5)  describes  the  rock,  which  he  submitted 
to  analysis,  as  an  aggregate  of  labradorite,  often  coarse 
^rained,  Avith  pyroxene  and  titanic  iron,  and  declared  it  to 
be  evidently  "a  bedded  metamorphic  rock."" 

§311.  Similar  anorthosite-rocks  Avere  known  to  exist  in 
the  gneissic  region  of  Norway,  and  had  been  by  Esmark 
called  norites,  from  the  name  of  the  country.  A  careful 
examination  by  the  writer  of  a  large  collection  of  these,  se- 
lected for  ornamental  jiurposes,  and  sent  by  the  Royal  Uni- 
versity of  Christiania  to  the  Paris  Exhibition  of  1807,  shoAved 
them  to  be  precisely  similar  to  the  labradorite-rocks  of 
North  America.  In  a  printed  notice  accompanying  this 
collection  it  was  stated  that  these  A'arious  rocks,  consisting 
of  labradorite  with  hypersthene,  diallage  and  bronzite.  had, 
in  th(^  geological  map  of  Southein  Norway,  published  in 
18(5(5,  b(>eu  designated  by  the  common  name  of  gabbro. 
This  notice  at  the  same  time  suggested  that  "the  name  of 
norite  should  be  preserved  for  certain  varieties  of  gabbro 
rich  in  labradorite,  which  varieties  may,  in  great  part,  Avith 
justice  be  called  labradorite-rock,  since  labrador-feldspar  is 
their  predominant  element." 


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TUE  LAKRADORITE  OR  NORIAN   SERIES.  E.   IGl 

§  312.  The  geological  map  of  Nonvay  above  refen'ed  to 
shows  that  tliese  so-called  gabbros  occupy  (lonsiderable  areas 
within  the  Laurentian  gneiss  region  of  Norway,  and  are  by 
the  authors  of  the  map.  KjeiMilf  and  Dalil,  regarded  as  erup- 
tive, though  they  are  des('ril)ed  by  them  as  often  ]>res«Mit- 
ing  the  characters  of  stratified  rocks.  In  fart,  the  banded 
stratiform  structure  of  tlu'se  Norwegian  norites  is  as  clearly 
marked  as  that  of  any  of  those  of  North  America,  horn 
wliicli  they  cannot  be  distinguished.  Of  the  above  collec- 
lion,  the  norites  of  Sogndal  and  Egei-sund  presented  line 
varieties  of  grayish  or  brownish  violent  tints,  wliile  a  dark 
violet  norite  comes  from  Krageroc.  and  also  from  Laiigoo 
and  Gomoii,  and  a  white  gi'anular  variety  from  the  (fiilf  of 
Laerdal,  in  the  diocess  of  Bergen.  Very  IxMiiriful  varie- 
tius  of  coarsely  granitoid  violet  coloi-ed  norite,  often  oi)ales- 
cent,  are  brought  from  Southern  Russia,  wdiere  the  rot^k  is 
said  to  form  a  mountain  mass  in  the  government  of  Kiew. 
For  further  details  on  the  norites,  both  of  Norway  and  North 
America,  see  the  writer's  essay  On  Norite  Rock,  read  be- 
fore the  American  Association  for  the  Advancement  of  Sci- 
ence in  ISGO,  and  pnblished  in  the  American  Journal  of 
Science  for  Novemlx^r  of  that  year. 

§  813.  The  x>i'ior  name  of  norite  was,  in  accordance  with 
the  suggestion  of  the  Norwegian  geologists,  lienceforth 
adopted  for  these  rocks  in  America,  and  since  it  was  appar- 
ent that  they  form  a  stratiiied  series  entirely  distinct  from 
the  Laurentian,  the  Avriter,  in  his  address  before  the  Asso- 
ciation just  named,  in  tSTl,  substituted,  in  place  of  Upper 
Laurentian  and  Labradorian,  the  designation  of  the  Norian 
series  foi*  these  labradorite  or  anortlif)site  rocks,  (See 
further  his  Chemical  and  Geological  Essays,  pages  270-281). 
Nothing  more  is  known  of  the  norites  there  mentioned  as 
found  in  the  vicinity  of  St.  John,  New  Brunswick,  where 
they  occupy  a  small  area  in  a  greatly  disturbed  district; 
while  the  labradoritic  rocks  in  the  White  Mountains,  which 
had  by  Hitchcock  been  referred  to  norite,  are  now  found  by 
him  to  be  eruptive  masses.  A  few  scattered  erratic  blocks 
of  norite  have  been  found  on  the  New  England  coast,  near 
the  mouth  of  the  St.  Croix,  and  at  Marblehead,  Massachu- 
[K.  11] 


mi 


m 


162    E.       SIM'X'IAL    IlKPOUT.       T.   STFCKUY   HUNT,    1875. 


11 


setts,  wliil(3  the  occurrence  of  similar  masses  in  greater 
abundance  in  northern  New  Jersey,  suggests  tlu?  possible 
presence  of  the  Norian  aeries  among  the  crystalline  rocks 
of  the  Highlands. 

§  314.  The  presence  of  titanic  iron,  approaching  menac- 
canite  or  ilnienite  in  conii)osition,  seems  to  be  very  charac- 
teristic of  the  Norian  rocks.  In  Canada,  at  St.  Urljain,  at 
Lake  St.  John  and  in  the  Bay  of  Seven  Islands,  are  found 
masses  of  thi.s  mineral  so  large  as  to  attract  attention  as  to 
a  possible  ore  of  iron  (Geology  of  Canada,  pages  501,  754, 
and  report  for  1866-09,  pages  252,  200).  Similar  ores  are 
found  with  the  norites  of  Krageroe  and  Egersund  in  Nor- 
way, and  the  writer  has  found  an  iron-ore  from  Skye  to  be 
of  the  same  sj^tecies. 

§  315.  A  blue  granitoid  norite,  and  a  titanic  ore  like  those 
of  Canada  and  Norway,  are  found  associated  in  Wyoming, 
on  the  Laramie  plains,  near  the  Chugwater  creek,  and  were 
identified  and  described  from  specimens,  by  the  writer,  in 
the  Transactions  of  the  American  Institute  of  Mining  Engi- 
neers, in  1873  (Vol.  I,  335).  Mr.  Arnold  Hague,  in  the  Sur- 
vey of  tlie  Fortieth  Parallel  (volume  II,  pages  13-10)  has 
since  described  under  the  name  of  gabbro,  .his  same  norite, 
which,  from  its  analysis,  is  shown  to  be  a  nearly  pure  labra- 
dorite,  while  the  iron-ore  holds  about  one  fourth  its  weight 
of  titanic  oxyd.  These,  though  by  him  regarded  as  erui)- 
tive,  suggest  the  existence,  in  this  region,  of  an  area  of 
stratified  Norian  rocks. 

§  310.  Titanium  is  not  unl■mo^vn  in  the  Laurentian  and 
Huronian  iron-ores,  though  seldom  in  such  amounts  as  to 
be  prejudicial  to  their  use  in  metallurgy,  but  in  all  the 
cases  with  Avhicli  the  writer  is  acquainted,  the  iron-ores  of 
the  Norian  are  so  higldy  charged  with  it  as  to  be  unfit  for 
use  in  the  blast-furnace.  Having  been  called  in  1870  to 
examine  the  large  deposits  of  highly  titaniferous  ores  near 
Westport  in  Essex  county,  New  York,  these  were  found  to 
be  included  in  tlie  Norian  rocks  of  that  region,  which  offer 
a  marked  contiast  to  the  Laurentian  gneisses  near  by,  in 
which  are  included  the  magnetic  ores  so  extensively  mined 
in  the  vicinity  of  Port  Henry  (Tnins.  Amer.  Inst,  of  Mining 
Engineers,  Vol.  I,  page  335). 


LEEDS  ON  THE  NORIAN  SEKIES. 


E.    103 


'lit 


§  317.  Prof.  Jjimes  Hull  has  since  examined  this  ie;:fi()n, 
and  in  a  communication  to  the  American  Association  for 
the  Advancement  of  Science,  in  1870,  has  conlirmcd  the 
writer's  observations.  Hall  distinguishes  two  parts  in  tiie 
crystalline  rocks  of  Essex  county,  the  lower  consisting  of 
coarse  I'eldspathic  and  quartzosc  rocks  (gneisses)  often  with 
black  hornblende  and  with  garnet,  including  great  beds  of 
magnetic  iron-ore.  These  rocks  are  ''succeeded  by  massive 
beds  of  labradorite-rocks.  This  x^a^i't  of  tlie  formation  is 
marked  by  extensive  beds  of  titaniferous  iron-ore.  The 
succession  is  however  unconformable,  and  the  interval  be- 
tween the  two  series  of  rocks  is  not  determined ' '  (American 
Journal  of  Science,  III,  xii,  299). 

§  318.  The  JS'orian  region  in  Essex  county,  New  York, 
rises  into  considerable  hills,  the  highest,  Mouni  Marcy,  being 
5,400  feet  above  the  sea,  and  extends  along  the  hore  of  Lake 
Champlain,  from  near  Westport  to  Port  Kent.  The  rail- 
way between  these  two  points,  in  its  course  around  Wills- 
borough  Bay,  is  cut  for  about  five  miles  through  the  Norian 
rocks,  which  may,  there  be  studied  to  great  advantage.  Prof. 
Albert  R.  Leeds,  of  Iloboken,  New  Jersey,  has  lately  de- 
voted much  attention  to  these  rocks  in  Essex  county,  and 
has  embodied  his  observations  in  a  paper  read  before  the 
New  York  Academy  of  Science,  December  11,  1870,  and 
published  under  the  title  of  "Notes  on  the  Lithology  of 
the  xVdirondacks,"  in  the  American  Chemist  for  March  1877, 
which  forms  a  very  important  contribution  to  the  hiatory 
of  the  Norian  series.  In  this,  besides  giving  an  analysis  of 
the  previous  observations  of  Emmons,  and  of  the  present 
writer,  he  has  made  careful  chemical,  mineralogical  and  mi- 
croscopical studies  of  the  Norian  roclvs  collected  by  himself 
in  Essex  county. 

§  319.  Rejecting  the  names  of  gabbro,  hyperite,  diorite 
and  diabase,  by  which  many  would  designate  these  rocks, 
he  has  called  them  all  norites.  Some  of  these  are  described 
as  porx)hyritic  from  the  presence  of  polysynthetic  ma.-les 
of  smoky  bl  ii(3  labradorite  in  a  granular  or  crypto-crystalline 
matrix,  which  is  often  yellowish  in  color.  In  some  cases 
this  matrix  or  paste  is  almost  entirely  wanting,  while  in 


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164   E.      SPECIAL    REPORT.      T.  STERRY  HUNT,  1875. 

Others,  from  the  absence  of  the  crystals,  we  have  a  compact 
greenish  feldspar-rock,  with  some  admixed  diallage  and 
red  garnet.  This  latter  mineral  is  a  common  element  in 
these  rocks,  and  is  generally  associated  with  the  non-feld- 
spathic  portion,  garnet  often  bordering  the  masses  of  dial- 
lage.  in  some  instances,  by  the  disapi)earance  of  feldspar, 
and  the  j)redominance  of  garnet,  with  some  hornblende,  the 
rock  passes  into  a  grenatite.  Other  varieties  are  described 
as  hypersthenic,  liornblendic,  and  pyroxenic  norites.  There 
are  also  pyroxenites  with  bnt  little  admixture  of  feldspar, 
and  the  pyroxene  is  sometimes  broadly  foliated  and  dial- 
lagic,  and  at  other  times  green  and  granular  like  coccolite. 
Quartz  is  generally  present,  but  for  the  most  part  in  minute 
particles  only  visil)le  under  the  microscope.  Titanic  iron  is 
always  found  in  these  rocks,  sometimes  with  magnetite. 

§  319.  Of  two  analyses  by  Prof.  Leeds,  one  of  the 
bluish  feldsi)ur  from  the  hyx)ersthenic  granitoid  norite 
which  forms  the  summit  of  Mount  Marcy,  and  the  other 
from  the  yellowish  crypto-crystalline  paste  of  a  porphyritic 
norite,  both  liave  very  nearly  the  composition  of  a  proper 
labradorite.  He  also  analyzed  the  hypersthene  and  the 
diallage  of  these  rocks.  (A  yeliowish-green  gi'anular  ep- 
idote  has  been  found  by  the  writer  accompanying  a  white 
feldspar  in  one  of  the  nearly  compact  norites  from  this 
region. )  Prof.  Leeds  has  also  given  the  anal  ysis  of  a  reddish 
granular  quartzo-feldspathic  rock  found  among  the  norites, 
\vhich  contained  admixtures  of  menacannite  and  magnetite, 
and  yielded  seventy -six  per  cent,  of  silica,  over  live  per 
cent,  of  potash,  and  three  of  soda,  with  but  traces  of  lime. 
From  its  chemical  composition,  and  its  microscopic  charac- 
ters, it  would  seem  to  represent  one  of  the  orthoclase  rocks 
which  have  been  described  as  occurring  in  the  Norian  series. 

Prof.  Leeds  notes  tliat  these  norites  are  evidently  stratified, 
and  are  clearly  to  be  distinguished  from  the  eruptive  doler- 
itic  rocks,  also  described  by  him,  which  traverse  them. 
These  dolerites  have  however  the  same  constituent  minerals, 
and,  he  suggests,  may  perhaps  have  been  derived  fi'om 
deeply-seated  portions  of  pyroxenic  norites. 

§  320.     The  calcareous  portions  of  the  Lauren tian  series 


i. 


LIMESTONE  VEINS   OF   THE   LAURENTIAN.        E.    165 


eries 


are  in  part  pure  limestones,  and  in  part  either  dolomites,  or 
limestones  more  or  less  maguesian.  They  are  themselves 
crystalline,  and  abound  in  crystalline  species  well  known  to 
mineralogists.  The  geognostical  relations  of  these  calca- 
reous rocks  offer  many  x^oints  of  interest.  We  have  seen 
that  Maclure  early  recognized  the  fact  that  the  crystalline 
limestones  of  his  Primitive  Gneiss  formation  were  inter- 
stratified  with  the  gneissic  and  granite-like  rocks  (§  40). 
This  view  was  also  shared  by  Nuttall,  but  Emmons  classed 
the  crystalline  limestones  of  northern  Now  York  among 
the  unstratified  rocks.  Mather,  while  admitting  the  strati- 
fied character  of  some  of  them,  conceived  that  certain  lime- 
stones of  the  region  just  named  were  eruptive,  and  had  been 
"injected  in  a  fluid  state."     (§  82-87.) 

§  321.  The  studies,  by  the  writer,  of  the  Laurentian 
limestones  of  Canada  and  New  York,  enabled  him,  in  1800, 
to  explain  these  seeming  contradictions  by  showing  that 
besides  the  stratified  limestones,  which  are  clearly  indi- 
genous, and  form  contemporary  portions  of  the  La"rentiau 
series,  there  are  endogenous  masses  or  concretionary  veins 
of  crystalline  carbonate  of  lime,  which  traverse  the  gneissic 
rocks  of  the  series  and,  containing  the  same  mineral  species 
as  the  bedded  limestones,  had  hitherto  been  confounded 
with  these. 

§  U22.  The  history  alike  of  the  limestone  beds  and  the 
calcareous  vein-stones  of  the  Amcn-ican  Laurentian,  including 
their  mineralogy  and  lithology,  as  well  as  the  history  of 
similar  crystalline  limestones  in  various  parts  of  Europe, 
is  discussed  in  the  rejoort  of  the  Geological  Survey  of 
Canada  for  1803-00,  pnges  181-229. 

Tlierein,  on  page  210,  the  deposits  of  franklinite  and 
zincite,  with  willemite,  found  in  Franklin  and  Sterling,  New 
Jersey,  were  noticed,  on  the  authority  of  II.  1).  Rogers,  as 
occurring  in  veins,  while  at  the  same  time  a  doubt  was 
expressed  "whether  these  ores  do  not,  like  the  magnet- 
ites, occur  in  the  stratified  rocks  of  the  region."  The 
writer's  subsequent  studies  in  the  localities  menticmed  have 
satisfied  him  that  the  ores  in  question  are  really  indigenous 
interstratified  masses. 


166   E.       SPECIAL   REPORT.      T.  8TERRY  HUNT,  1875. 

The  above  essay  was  reprinted,  with  some  additions,  in 
the  Report  of  the  Regents  of  the  University  of  New  York 
for  1867,  Appendix  E,  and  a  summary  of  its  principal 
points  will  be  found  in  Chemical  and  Geological  Essays, 
pages  208-219. 

§  322.  Masses  of  crystalline  limestone  containing  such 
characteristic  minerals  as  hornblende,  pyroxene,  serpentine, 
chondrodite,  mica,  apatite  and  graphite  may  belong  either 
to  beds  or  to  veins,  and  in  small  outcrops  it  is  sometimes 
difficult,  if  not  impossible,  to  distinguish  one  from  the 
other.  The  veins  are  often  of  large  size,  and  not  unfre- 
quently  contain  larger  or  smaller  masses  of  the  wall-rock. 
Such  an  occurrence  appears  to  have  been  noticed  by  Mather, 
who  described  a  cliff  of  crystalline  limestone,  as  having 
"  a  mass  of  stratified  hornblendic  gneiss  distinctly  imbedded 
in  it."  (§  35).  Similar  cases  are  found  in  North  Burgess, 
in  the  province  of  Ontario. 

§  323.  A  good  example  of  this  phenomenon  is  seen  near 
the  town  of  Port  Henry,  in  Essex  County,  New  York,  in  a 
quarry  whence  limestone  has  been  got  for  the  blast-fur- 
naces. Here,  irregular  elongated  angular  fragments  of 
dark  hornblendic  gneiss,  from  two  inches  to  a  foot  in  thick- 
ness, Avere  found  completely  enveloped  in  crystalline  car- 
bonate of  lime.  In  1877,  five  such  masses  of  gneiss  were 
exposed  in  an  area  of  a  few  square  yards.  One  of  these. 
a  thin  plate  of  the  gneiss,  having  been  broken  in  two,  the 
enclosing  calcareous  matter  filled  the  little  crevice,  keep- 
ing the  fragments  very  nearly  in  their  place.  The  carbon- 
ate of  lime,  which  is  coarsely  granular,  and  contains  some 
graphite  and  pyrite,  is  banded  with  lighter  and  darker 
shades  of  color,  and  one  of  its  layers  was  marked  by  the 
presence  of  crystals  of  green  pyroxene  and  of  broAvn  spliene. 

The  contact  of  this  mass  with  the  surrounding  gneiss, 
whicli  is  near  by,  is  concealed.  No  serpentine  was  found 
in  this  limestone,  though  it  abounds  in  a  limestone  quarried 
in  the  vicinity.  About  half  a  mile  to  the  north  is  still  an- 
other quarry,  opened  in  a  great  breadth  of  more  finely 
granular  and  somewhat  gi-aphitic  limestone,  which,  near  its 
border,  presents  tliree  beds  of  two  or  three  feet  each,  inter- 


LIMESTONE  VEINS   OF  THE  LAUKENTIAN.        E.    167 

stratified  with  the  enclosing  gneiss.  The  first-described 
locality  seems  clearly  to  be  a  brecciated  calcareous  vein 
enclosing  fragments  of  the  gneiss  wall-rock. 

§  324.  Prof.  James  Hall  appears  to  have  observed  simi- 
lar cases.  In  the  paper  quoted  above  (§  317)  he  gives  some 
account  of  the  crystalline  limestone,  as  seen  in  the  vicinity 
of  Port  Henry,  and  says:  "Sometimes  it  is  conspicuously 
brecciated,  and  contains  fragments  of  gneiss-rock,  which 
seem  to  have  been  derived  from  the  strata  below,  upon 
which  the  rock  lies  unconformably."  He  concludes  that 
these  crystalline  limestones  do  not  belong  either  to  the  Lau- 
rentian,  or  to  the  unconformably  overlying  labradorite  (No- 
rian)  recks,  but  to  a  newer  formation.  The  inclusion  of 
fragments  of  gneiss  is  however  the  only  ground  assigned  in 
support  of  the  view  that  these  calcareous  masses  belong  to 
an  unconformably  overlying  formation,  and  the  facts  ob- 
served by  the  writer  lead  to  the  conclusion  that  the  cal- 
careous masses  of  the  region,  except  so  far  as  they  form  in- 
terstratified  portions  of  the  Laurentian  or  of  the  Norian 
series,  are  to  be  regarded  as  endogenous  masses  or  vein- 
stones— the  eruptive  limestones  of  Emmons  and  of  Mather. 
The  banded  or  stratiform  arrangement  shown  in  the  distri- 
bution of  the  foreign  minerals  in  some  of  these,  is  to  be 
compared  with  the  similar  structure  often  observed  in  gran- 
itic and  other  concretionary  veins.  See  for  a  discussion  of 
this.  Chemical  and  Geological  Essays,  pages  193,  198 ;  and 
as  regards  the  banded  structure  resulting  from  the  How  of 
eruptive  rocks,  page  18G. 

§  325.  Tlie  indigenous  crystalline  limestones  of  the  No- 
rian, so  far  as  known,  resemble  those  of  the  Laurentian. 
The  hyi^ersthene  rocks  of  New  York,  are,  according  to  Em- 
mons, intermixed  and  penetrated  with  a  crystalline  lime- 
stone containing  the  usual  characteristic  minerals,  (§  88) 
from  which  we  may  perhaps  infer  that  the  limestone-veins 
are  common  to  the  Norian  and  Laurentian  series.  The  age 
of  these  veinstones  is  greater  than  that  of  the  Lower  Cam- 
brian series,  since  the  Potsdam  sandstone  in  South  Burgess, 
Ontario,  has  been  seen  to  rest  upon  the  eroded  outcrop  of 


p1 


I 


it 


m 


(  ; 


i 


168  E.      SPECIAL    KEPORT.      T.  STERTIY  HUNT,  1875. 


rolled  fragments 


of 


one  of  these  veins,   and  to  include 
apatite,  apparently  derived  from  it, 

§  32().  The  finding  of  the  organic  form  known  as  Eozoon 
Canadense  marks  an  epoch  in  the  history  of  the  Laurentian 
series,  and  the  history  of  its  discovery  has  been  well  told 
by  Dr.  J.  W.  Dawson,  in  his  excellent  little  volume  on  the 
subject,  entitled  The  Dawn  of  Life  (London,  1875).  There 
are  however  two  slight  corrections  to  be  made  tlierein,  the 
first  of  which  regards  the  argument  urged  by  the  present 
writer  in  proof  of  the  existence  of  organic  life  in  the  Laur- 
entian age.  This,  on  page  27  of  the  volume  just  cited, 
(and  previously  in  the  Quarterly  Journal  of  the  Geological 
Society,  Vol.  xxvi.  page  113)  is  said  to  have  been  x)ut  forth 
in  18G1,  or  three  years  after  the  discovery  of  the  remains 
of  Eozoon,  when  they  were  already  supposed  to  be  organic. 
In  fact,  the  language  there  quoted  from  an  article  in  the 
American  Journal  of  Science  of  that  date,  was  but  a  repe- 
tition of  views  put  forward  in  the  same  journal  for  May, 
1858,  II,  XXV.  420)  where  it  was  declared  that  a  great  mass 
of  evidence  "points  to  the  existence  of  organic  life  even 
during  the  Laurentian  or  so-called  Azoic  period."  See  also 
Chemical  and  Geological  Essays,  pages  13  and  302. 

§  327.  It  was  in  the  autumn  of  1858  that  Mr.  John  Mc- 
Mullen,  then  attached  to  the  survey  of  Canada,  and  an  in- 
telligent and  enthusiastic  student  of  geology,  who  Avas  fa- 
miliar with  the  above  views  on  this  question,  and  fully 
ai:)preciated  the  importance  of  such  a  discovery,  found  in 
the  crystalline  limestone  at  the  Grand  Calumet  Falls,  on  the 
Ottawa,  specimens  of  what  he  believed  to  be  a  fossil  coral 
These,  he  lirst  of  all  submitted  to  the  writer,  who  then  com- 
pared them  with  Stromatopora,  and  laid  them  before  the 
director  of  the  survey.  The  appearance  of  these  specimens 
at  once  recalled  certain  specimens  similar  in  form,  which 
had  been  collected  in  North  Burgess  by  Dr.  Wilson  of 
Perth,  Ontario,  and  by  him  i)resented  to  the  museum  of 
the  geological  survey,  l>ut  had  not  hitherto  been  critically 
examined,  ncn*  suspected  to  be  organic.  The  careful  mi- 
croscopic study  of  the  specimens  from  these  two  localities, 
which  were  submitted  to  Dr.  Dawson,  failed  to  give  any 


-t^— T 


HISTORY    OF   EOZOON. 


E.   IGO 


satisfactory  evidence  of  the  true  nature  of  these  singular 
forms,  which  were  however  described  as  probably  of  or- 
ganic origin,  and  ligured  in  1802,  on  page  49  of  tlie  Geology 
of  Canada,  (§  2U7.) 

§  '328.  In  1803,  some  blocks  of  serpentinic  limestone,  pro- 
cured by  the  geological  survey,  and  destined  for  the  marble- 
cutter,  were  observed  by  Logan  to  contain  in  abundance, 
forms  apparently  identic  il  with  those  above  noticed,  but 
more  x^erfectly  preserved.  These  blocks  had  been  got  by 
Mr.  James  Lowe  from  a  quarry  in  Cote  tSt.  Pierre,  in  the 
seignory  of  La  Petite  Nation,  which  lies  on  the  north  side 
of  the  Ottawa  River,  immediately  to  the  west  of  Gren- 
ville.  This  limestone-quarry,  according  to  Logan,  is  on  the 
upper  limestone  band  of  the  Grenville  division  of  the 
Laurentian  (§  299).  The  precise  horizon  in  the  series  of  the 
specimens  from  the  other  localities  named  is  not  known. 

Specimens  from  this  new  locality  were  at  once  placed  in 
the  hand  of  Dr.  Dawson,  who  early  in  1804  declared  that 
they  were  the  remains  of  a  foraminiferal  organism,  to  which 
he  gave  the  name  of  Eozoon  Canadcnse.  The  iirst  an- 
nouncement of  this  was  made  bv  the  writer  in  the  American 
Journal  of  Science  for  May,  18G4,  and  in  February,  1805 
there  appeared  in  the  Quarterly  Journal  of  the  Geological 
Society  of  London,  a  description  of  Eozoon  by  Dr.  Dawson, 
together  with  discussions  of  its  geological  and  mineralogical 
relations  by  Logan  and  the  present  writer.  For  further  de- 
tails, and  for  the  subsequent  history  of  Eozoon,  the  reader 
is  referred  to  Dr.  Dawson's  volume  already  quoted,  and 
also  to  Chemical  and  Geological  Essays,  pages  o03,-4ll. 

§  329.  Within  the  liniits  of  the  region  in  Canada  origi- 
nally described  as  Laurentian,  there  are,  besides  the  Lauren- 
tian and  Norian  series,  other  and  more  recent  crystalline 
stratified  rocks,  which  require  description.  An  area  of 
these  has  for  many  years  been  known  in  the  county  of 
Hastings,  which  extends  northward  from  the  eastern  por- 
tion of  Lake  Ontario.  The  rocks  in  question  were  Iirst 
noticed  by  ;Mr.  Murray  in  his  report  for  1852  (pages  l()4-l()r)) 
as  '•interesting  diversities  in  the  Laurentian  series,"  seen 
in  the  towns  of  Madocand  Belmont.     They  were  described 


ii 


^1 


f''  i\ 


fl 


170  E.      SPECIAL   REPORT.      T.  STERRY  IHrNT,  1875. 

by  him  as  consisting  of  fine  grained  silicious  clay-slate, 
passing  into  micaceous  and  talcose  slates,  often  calcareous 
and  pyritiferous,  and  sometimes  holding  crystals  of  mag- 
netite, associated  with  which  were  great  beds  of  conglom- 
erate, including  pebbles  of  quartzite,  with  others  of  green- 
stone and  of  a  reddish  feldspathic  rock.  In  addit'^n  to 
these,  were  beds  of  granular  magnesian  limestone,  some- 
times becoming  schistose.  These  strata  were  said  to  have  a 
moderate  dip  to  the  southeast,  but  their  relation  to  the 
gneissic  rocks  of  the  surrounding  region  was  not  determined. 

§  330,  The  schistose  rocks  in  the  townships  named,  and 
in  some  others  adjacent,  were  again  examined  in  1864,  by 
Mr.  Thomas  Macfarlane,  and  noticed  by  him  in  the  report  for 
1863-GG  (pages  93-94).  The  argillaceous  and  micaceous  slates, 
associated  with  conglomerates,  were  further  described, 
and  were  said  to  graduate  into  the  limestones  of  the  series, 
of  which  two  varieties  were  noted,  the  one  distinctly  crys- 
talline, white  or  gray  in  color,  often  banded,  sometimes 
micaceous,  and  quarried  as  a  marble,  the  other  finer  grained, 
less  crystalline,  and  of  a  dark  gray  color. 

Macfarlane  also  noticed  in  Elzivir  and  Madoc  considerable 
areas  of  another  group  of  strata,  distinct  alike  from  the 
last  and  from  the  gneisses  of  the  region,  and  consisting 
chiefly  of  pyroxenic  and  homblendic  rocks,  the  latter  some- 
times becoming  micaceous.  These  were  described  as  form- 
ing varieties  of  diabase  and  of  diorite,  and  passing  into 
diorite-slate  and  chlorite-slate.  He  also  noticed  the  occur- 
rence of  a  red  petrosilex  porj)hyry.  The  rocks  of  this 
group  were  found  by  him  to  include  the  magnetic  iron- ores 
of  Marmora  and  Seymour. 

§  331.  Macfarlane  was  disposed,  on  lithological  grounds, 
to  regard  these  two  groups  of  schistose  rocks  as  belonging 
to  a  newer  series  than  the  surrounding  Laurentian  gneisses, 
and  compared  some  of  them  to  the  Huronian,  but  Logan, 
in  a  foot-note  to  the  report,  on  page  93,  objected  this  view, 
and  suggested  that  "the  Hastings  rocks  may  be  a  higher 
portion  of  the  Lower  Laurentian  series  than  we  have  met 
elsewhere."  He  further  remarked  that  wiiile  these  rocks 
offer  certain  resemblances  with  the  Huronian,  and  with  the 


THE  HASTINGS  SERIES. 


E.    171 


crystalline  rocks  of  the  Green  Mountain  range  in  Cnnada, 
"the  micaceous  limestones  of  Hastings  more  closely  resem- 
ble the  micaceous  limestones  which  run  from  Eastern  Can- 
ada into  Vermont,  on  the  east  side  of  the  Green  Mountains." 
These,  however,  it  was  argued  by  him,  from  the  evidence 
of  associated  fossiliferous  strata,  are  Devonian,  while  "the 
Hastings  limestones,  which  are  highly  corrugated,  are  uncon- 
formably  overlaid  by  horizontal  beds  of  the  Birdseye  and 
Black-River  limestones."  He  added  in  proof  of  their  re- 
lations to  the  Laurentian,  that  these  Hastings  limestones 
hold  Eozoon  Cariadense. 

§  332.  Fragments  of  Eozoon  had  already  been  detected 
by  Dawson  in  1866,  in  a  specimen  of  the  limestone  from 
Madoc,  collected  many  years  previously  by  Logan.  In 
that  same  year  Mr.  Henry  G.  Vennor  was  sent  to  begin  a 
detailed  examination  of  the  rocks  of  the  "  Hastings  series," 
as  it  was  then  called,  and,  his  attention  having  been  called 
to  this  matter,  he  found  in  the  township  of  Tudor,  numerous 
specimens  of  the  Eozoon  "imbedded  in  an  impure  earthy 
dark  gray  limestone,  with  which,  and  with  carbonaceous  mat- 
ter, the  cavities  of  the  white  calcareous  skeleton  are  filled  ; " 
unlike  the  greater  number  of  the  specimens  from  the  Ottawa, 
which  are  filled  by  serpentine  or  by  pyroxene.  These  speci- 
mens were  examined,  figured  and  described  by  Dawson, 
and  an  account  of  their  geological  relations,  so  far  as  then 
known,  was  given  by  Logan  in  the  Journal  of  the  Geologi- 
cal Society  for  August,  1867.  He  there  expressed  the 
opinion  that  "  the  Hastings  series  may  be  somewhat  higher 
than  that  of  Grenville." 

§  333.  In  the  report  for  1866-69  (page  144,)  and  in  that  for 
1870,  (page  310)  Mr.  Vennor  gave  the  results  of  his  obser- 
vations in  Hastings  and  some  adjoining  counties,  during  the 
four  years,  1866-69,  his  materials  having  previously  been 
submitted  to  the  examination  of  the  waiter.  The  various 
crystalline  rocks,  with  a  northeast  and  southwest  strike, 
come  out  from  beneath  the  fossiliferous  limestones  of  the 
Trenton  group,  which  have  here  a  gentle  southward  dip,  and 
occupy  the  southern  townships  of  Hastings  county,  besides 
forming  some  small  outliers  further  north,  in  Elzivir,  Mar- 


.rl 


% 


If 


172  E.      SPECIAL   REPORT.      T,   STERRY   HUNT,    1875. 

mora  and  Madoc.     These  crystalline  rocks  were  included  in 
three  groups,  as  follows,  in  ascending  order: 

I.  A  miuss  of  reddish  granitoid  rock  with  olisnuro  marks  of 

striitifictitioii,  followed  by  several  thousand  feet  of  gneisses 
with  crystallino  limestones  and  beds  of  magnetite.  Tlicse 
rocks  liad  all  the  cliaracters  of  the  Laurentiaii,  to  which 
they  wore  referred. 

II.  A  series  of  dioritic  and  diabasic  rocks,  massive  and  snhLs- 
tose,  sometimes  conglomerate,  passing  into  chloriticfichists, 
with  beds  of  steatite,  magnesian  limestone,  and  petrosilex, 
and  with  magnetite  and  hematite  ores.  These  rocks,  luiving 
an  estimated  thickness  of  nearly  10,000  feet,  were  regarded 
as  Iluronian. 

III.  The  series  of  bluish  and  grayish,  occasionally  glossj' 
slates,  quartzites,  conglomerates,  and  limestones,  already 
described  in  §  .'5.10,  .l.'JI.  Tlie  conglomerates  include  peb- 
bles of  quartzite,  of  greenstone,  and  of  gneiss.  The  crys- 
talline dolomites  are  near  the  b.xso  of  the  series,  while  the 
fine  grained,  grayish,  more  or  less  sciiistose  and  eartliy 
limestones,  containing  E(>zoon,  form  the  upper  1,000  leet 
of  the  series,  which  has  a  probable  thickness  of  about 
3,800  feet. 

§  334.  The  provisional  name  of  the  Hastings  series  will 
be  reserved  for  division  TIL  The  strata  of  both  I  and  II 
are  described  as  generally  vertical  or  highly  inclined.  The 
strata  of  division  HI  are  arranged  in  several  synclinals, 
with  moderate  dips,  and  rest  unconformably  both  on  the 
Laurentian  and  upon  the  Iluronian  series.  The  frequent 
aV)sence  of  the  latter  at  the  base  of  the  Hastings  series,  in- 
dicates the  existence  of  two  stratigraphical  breaks  in  the 
succession  of  these  crystalline  strata.  The  rocks  of  divis- 
ions II  and  III  are  traced  northeastwards,  out  of  the  county 
of  Hastings,  across  that  of  Lenox  and  Addington,  and  of 
Frontenac,  into  Lanark  and  Renfrew,  and  nearly  to  the 
Ottawa  river,  a  distance  of  about  eighty  miles  along  the 
strike. 

§  335,  There  appears  however,  to  be  still  another  group  of 
crji'stalline  rocks  in  the  region  under  examination.  The 
rocks  of  the  Hastings  series,  in  the  township  of  Levant,  are 
bounded  to  the  west  by  an  elevated  ridge  of  the  underlying 
red  Laurentian  gneiss,  by  which  they  are  separated  from 


THE   MICA-SCHIST   SERIES. 


E.  173 


a  series  of  mica-sohisfs  and  gneisses.  These  extend  north- 
ward through  Levant,  Pnlmerston,  and  Blytlitield,  where 
they  are  found  dipping  at  low  angles  to  the  east  nnd  west, 
occasionally  attaining  4.')°,  and  soniftiines  Uf^arly  liorizon- 
tal.  They  consist  of  friable  (piai'tzose  mica-schists,  some- 
times line  grained  and  ferruginous,  but  often  made  up  in 
great  part  of  large  distinct  laminae  (-)f  silvery-white  mica. 
With  these  are  associated  grayisli  white  tine-grained 
gneisses,  bla(;k  hornblendic  beds,  and  small  bands  of  gran- 
ular limestone.  These  rocks  were,  in  the  report  for  1870, 
(l)age  311)  compared  with  the  mica-schists  and  gneisses  of 
the  AVhite  Mountain  series,  and  with  similar  rcx'ks  from 
about  Lake  Superior.  At  the  same  time,  they  were  said  to 
resemble  some  parts  of  the  Hastings  series,  as  seen  in  Ma- 
doc  and  Tudor. 

§  330.  In  the  report  for  1874  (page  124)  Mr.  Vennor  has 
farther  described  this  so-called  Mica-Schist  series,  whicli  is 
said  to  have  a  breadth  of  about  one  and  a  half  miles  in  the 
first  two  townships  mentioned  above,  and  to  have  to  the 
west  of  it  a  considerable  area  of  the  gi'ay  line-gi-ained  and 
friable  gneisses.  From  tlie  relations  of  tliese  to  certain 
similar  strata  found  farther  to  the  southeast,  Vennor  con- 
cludes tliat  these  gneisses  and  mica-scliists  occupy  a  posi- 
tion above  division  II,  and  beneath  tlie  limestones  of  III. 
Their  precise  relations  to  these  latt(M'  does  not  however  ap- 
pear. The  mountain-belt  of  red  granitoid  gneiss,  already 
described  as  separating  these  limestones  and  calcareous 
schists  on  the  east  from  the  Mica-Schist  series  on  the  west, 
has  a  uniform  eastward  dip,  and  seems  to  overlie  the  lat- 
ter, an  appearance  supposed  by  Vennor  to  be  due  to  an 
uplift  of  the  older  formation. 

In  the  report  last  quoted  there  are  also  described,  under 
separate  heads,  groups  of  granitoid  and  hornblendic  rocks, 
which  are  probably  to  be  regarded  as  portions  of  one  or  the 
other  of  the  lower  divisions. 

§  337.  In  the  years  from  1869  to  1874  Vennor  was  en- 
gaged in  examining  the  distribution  of  the  crystalline  rocks 
to  the  southeastward  of  the  belt  above  mentioned,  across 
the  counties  of  Lanark  and  Frontenac,  as  far  as  the  western 


-■j- 


J 


'i 


i 


174  E.      SPKCIAL    REPORT.      T.    STERRY   HUNT,    1875. 

border  of  the  Ottawa  paleozoic  basin.  In  the  report  for  the 
last  mentioned  year  he  has  described  the  apparent  succes- 
sion of  the  Laurentian  rocks,  as  deduced  from  many  ob- 
servations in  the  townships  lying  to  the  westward  of  the 
town  of  Perth.  A  section  is  given  for  a  distance  of  )out 
six  and  a  half  miles  across  the  strike  of  the  rocks,  which 
have  a  constant  dip  to  the  southeast,  varying  from  forty  to 
eighty  degrees.  The  transverse  surface-measurements  and 
the  observed  dips  of  each  sub-division  are  given,  but  no  at- 
tempt is  made  to  estimate  the  vertical  thickness  of  the 
several  masses. 

§  338.  Beginning  at  the  west,  we  have,  in  ascending  order, 
as  f oUows : 

1.  Red  gneiss,  with  hornblcndlo  strata  (40O-fi0O)  .     3500  foot. 

2.  White  higlily  crystiillino  limestone,  witli  serpen- 

tine and  graphite,  and  some  interstratiiied  horn- 
blcndio  gneias  (40O-<)0O) 2G00    " 

3.  Ilornblendio  gneiss,  passing  into  gneissoid  and 

granitoid  liornblondic  diorites,  with  grains  and 
layers  of  epidote,  and  small  included  bands  of 
crystalline  limestone  (GQO-SGO) 5500    " 

4.  Gneissoid  rock  consisting  of  white  feldspar,  horn- 

blende and  quartz  (4r)O-80O) 1500     " 

5.  White  limestone,  coarsely  crj'stalline,  with  yel- 

low mica  and  graphite,  and  included  bands  of 
orthoclase  and  quart&rock  (00°) 2600     '• 

6.  Red  and  dark-colored  gneiss  and  hornblende- 

rock,  with  great  beds  of  magnetite  and  small 

bands  of  crystalline  limestone  (4oO-C0O)      .    .     7900     " 

7.  White  limestone,  very  coarsely  crystalline,  with 

disseminated  chor..rodite,  mica  and  graphite, 
and  including  layers  of  quartzite  and  horn- 
blendic  gneiss  (450-80°) 2G00     " 

8.  Red  granitic  and  hornblendic  gneiss  (450-80°)    2G0O     " 

9.  Crystalline  limestone  like  7,  ((iOO-SOO) ;  from  GO  to     100    " 

10.  Red  gneiss  and  hornblende  rock,  with  beds  of 

magnetite  (80°) 1300    " 

1 1.  Red  gneiss  with  marked  stratification,  becoming 

fissile  near  the  summit,  Avhere  it  holds  beds  of 
flesh-colored  crystalline  limestone  with  black 
spinel  (400-80°);  3000  to jOOO    " 


§  339.  In  view  of  the  persistent  eastward  dijD  of  these 
rocks,  and  the  great  difficulty  of  distinguishing  between 
different  masses  of  similar  gneisses  and  crystalline  lime- 


VETN'NOR  ON  TnE  LAURENTIAN. 


E.    175 


stones,  it  must  remain  a  question  whether  the  numbered 
sub-divisions  of  the  above  section  are  to  be  regarded  as 
members  of  a  consecutive  series,  or,  in  part,  as  repetitions, 
through  sliarp  overturned  folds,  or  through  faults,  as  ap- 
pears in  the  example  mentioned  in  §  330.  and  is  so  gener- 
ally the  case  in  the  strata  of  the  Atlantic  belt.  In  the  rase 
of  the  Ottawa  section,  (§298)  Logan  was  enabled  to  establish 
a  succession  by  showing  the  recurrence  of  the  masses  on 
the  opposite  sides  of  a  synclinal,  but  in  the  present  instance, 
the  immediate  superposition  of  the  paleozoic  strata,  to  the 
eastward,  makes  this  method  impossible. 

§  340.  To  the  above  series,  with  a  breadth  of  35,500  feet, 
succeeds,  according  to  Vennor,  another  calcareous  belt,  not 
described,  and  above  this  what  he  regards  as  the  highest 
member  of  the  system,  noticed  in  detail  in  the  report  for 
1872-73  (page  1C2)  as  lying  in  shallow  and  frequently  over- 
turned synclinals.  The  rocks  of  this  highest  member  are 
displayed  along  the  Rideau  canal,  in  North  Burgess,  North 
Crosby,  Bedford,  Loughborough  and  Storrington.  Their 
vertical  thickness,  in  dilferent  sections,  was  estimated  at  from 
2600  to  3900  feet.  They  are  described  as  reddish  gneisses, 
in  parts  abounding  in  red  garnet,  and  including  two  bands 
of  crystalline  limestone,  with  beds,  both  near  the  base  and 
the  summit  of  the  series,  characterized  by  a  predominance 
of  greenish  pyroxene,  and  designated  as  granitoid  pyrox- 
enic  gneisses,  passing  into  a  pyroxenic  schist  with  gar- 
nets. Apatite  is  found,  both  disseminated  and  fomiing 
layers,  alike  in  the  limestone  and  the  pyroxenic  rocks,  and 
also  in  short  irregular  veins  cutting  the  strata. 

The  mineralogy  and  lithology  of  tliese  rocks,  was  previ- 
ously described  at  some  length  by  the  writer  in  the  report 
of  18GG-G9  (pages  224-229)  and  the  characters  of  the  pyrox- 
enic masses  were  noticed  in  the  Geology  of  Canada  (1803) 
page  475,  where  the  associated  feldsi)ar  is  shown  to  be 
orthoclase,  often  with  sphene  and  with  qujirtz. 

§  341.  The  limestones  of  this  upper  member  which,  ac- 
cording to  Vennoi',  are  distinguished  from  those  below 
them  by  the  presence  of  apatite,  contain  the  Eozoon  found 
in  North  Burgess,  and  are  conjectured,  from  their  mineral 


'^ 


176  E,       SPECIAL   IIEPOIIT.       T.  STEKRY    HUNT,   1875. 


Ijil! 


II 


11    ■ 


!i' 


ir  '.'if. 


associations,  to  bb  the  same  v/ith  the  upper  limestone  band 
of  the  Grenville  series,  which  yiekls  the  Eozoon  of  Cute  St. 
Pierre,  In  chis  series,  according  to  Logan,  there  are  but 
tliree  great  limestone  bands  which,  with  their  associated 
gneisses,  were  described  as  constituting  an  ''upper  group" 
or  system,  overlying  the  ''lower  groiij)"  of  granitic  or  sye- 
nitic  gneisses  without  limestone,  which  we  have  called  the 
Ottawa  gneiss.  Mr.  Vennor,  in  a  late  note  in  the  American 
Journal  of  Science,  for  October,  1877,  api^ears  to  have  over- 
looked this  distiiu'tion,  pointed  out  by  Logan  in  18-17,  and 
claims  the  merit  of  having  distinguished  between  the  "old 
fundamental  red  gneiss  system"  without  limestones,  and 
the  great  oveilying  series  of  gneisses  with  crystalline  lime- 
stones, which  he  calls  his  "second  system,"  and  with  the 
limestone  bands  of  which,  he  asserts,  are  found  all  the  eco- 
nomic minerals  of  the  Laurentian.  This  was  already  pointed 
out  by  the  wri';er  in  the  report  for  ISOIi-GG  (page  18G)  where, 
after  d*^signating  these  limestone  bands  of  the  Grenville  se- 
ries, with  their  "attendant  pyroxenites,  amphibolites,  ser- 
pentines, magnetites,  etc,'  as  so  many  *'limest(megroui:)s," 
it  was  said  "  the  ores  of  iron,  copper,  nickel,  and  cobalt,  t]\e 
apatite,  mica  and  plumbago,  as  well  as  the  serpentines  and 
the  marbles  of  the  great  Lower  Laurentian  series,  belong, 
so  far  as  yet  known,  to  the  limestone  groups."  It  will  be 
remembered  that  the  teim  Lowei'  Laurentian,  then  used, 
included  both  the  lower  or  Ottawa  gneiss  and  the  rocks  of 
th(>  Grenville  series. 

Jj  842.  This  lower  gneiss  has  by  the  \vr:ter  been  compared 
witli  the  oldest  red  gneiss  of  Bavaria,  called  Bojian  by  G um- 
bel, and  the  Grenville  series  with  the  overlying  Hercynian 
gneiss  series  of  the  same  author,  which,  like  the  similar 
rocks  in  Canada,  includes  great  beds  of  crystalline  lime- 
stone, with  serpentine,  chondrodito  and  graphite,  and  con- 
tains Eozooii  CaiKKlcnse.  (American  Journal  of  Science 
for  July  1870,  II.  1.,  90.) 

^  'M'i\.  Mr.  Vennoi-  believes  that  there  is  a  want  of  con- 
formity between  the  lower  "system,"  or  the  Ottaw  agneiss, 
and  tlic  u])per  "system,"  or  Grenville  series,  and  farther 
suggests  that  tlie  rocks  of  divisions  II  and  III  in  Hastings 


DAWSON   ON  THE  HASTINGS  SERIES, 


E.    177 


5) 


Giirn- 
bynian 
limilar 

lime- 
H  con- 

•ience 

If  con- 
[iieiss, 
lirther 
stings 


county  (§333)  are  "simply  an  altered  condition,  in  their 
westward  extension,  of  the  lower  portion"  ol'  this  upper 
or  Grenville  seiies  ;  a  gratuitous  hypothesis,  in  support  of 
which  he  offers  no  argument,  and  which  it  is  unnecessary 
to  discuss.  The  only  i~)oint  of  relation  between  these  most 
unlike  groups  of  rocks  is  that  Eozoon  Canadense  is  com- 
mon to  the  limestones  of  the  Grenville  and  the  Hastings 
series. 

§  341.  Other  indications  of  organic  life  than  Eozoon  Can- 
adense, have  been  found  in  the  rocks  of  the  Hastings  series. 
In  his  original  paper  on  the  Eozoon,  in  ISCo,  Dr.  Dawson 
announced  that  in  some  of  the  dark-colored  imi)ure  lime- 
stones of  this  series,  from  Madoc  "there  are  iibres  and  gran- 
ules of  carbonaceous  matter,  which  do  not  conform  to  the 
crystalline  structure,  and  present  forms  quite  similar  to 
those  which  in  more  modern  limestones  result  from  the 


decomposition  of  algsD. 


Though  retaining 


mere  traces  of 


organic  structure,  no  doubt  would  be  entertained  as  to  their 
vegetable  origin  if  they  were  found  in  fossiliferous  lime- 
stones.'" lie  noticed  also  a  similar  Imiestone  from  the 
same  vicinity,  which  is  apparently  "a  iinely  laminated  sed- 
iment, and  shows  perforations  of  various  sizes,  somewhat 
scalloped  on  the  edges,  and  idled  with  grains  of  rounded 
silicious  sand."  Other  specimens  from  the  same  region 
were  said  to  have  indications  on  their  weathered  surfaces, 
of  similar  circular  perforations,  having  the  asx)ect  of  Sco- 
lithus  or  of  worm-burrows.  Some  of  these  markings  from 
Madoc  were  subsequently  figured  by  Dawson,  and  desig- 
nated "aimelid-buiTows,"  with  the  remark  that  "thnrecan 
be  no  doubt  as  to  their  nature,"  (Dawn  of  Life,  page  140). 
The  position  of  these  is  in  the  Hastings  series. 

^  342.  The  geologist  familiar  with  tlie  crystalline  strata 
of  the  Atlantic  belt,  finds  all  its  principal  types  repeated  in 
the  limited  region  included  in  Hastings  county  and  its 
northwestern  extension  towards  the  Ottawa.  The  rocks  of 
division  II  serve  to  connect  the  Huronian  of  Lakes  Superior, 
Huron  pud  Temiscaming  with  the  similar  rocks  of  north- 
esistern  America,  where  also  the  mica-schists  resembling 
those  just  noticed  are  widely  spread.  Rocks  of  this  latter 
[E.  12] 


i 


i 


\f 


1^ 

I 


I  -  I 


178  E.      SPECIAL   REPORT.      T,    STEKRY   HUNT,    1875. 

type  were  noticed  in  1824  by  Dr.  Bigsby,  about  Lake  La- 
croix  and  Rainy  Lake,  to  tlie  northeast  of  Lake  Superior, 
and  both  these  and  the  cliaracteristic  rocks  of  the  Huron- 
ian  were  then  described  by  that  excellent  observer,  (Ameri- 
can Journal  of  Science,  I,  viii,  Gl).  These  various  crys- 
talline stratii  were,  by  him,  conceived  to  belong  to  what, 
in  the  language  of  the  time  were  called  "transition  rocks." 
From  these  descrii)tions,  and  from  the  examination  of  collec- 
tions, the  writer,  while  noticing  in  1861,  the  observations  of 
Bigsby,  asserted  "  the  lithological  and  mineral  characters  of 
these  crystalline  strata  seem  to  be  distinct  from  those  of  the 
Laurentian  system,  and  to  resemble  those  of  the  Appala- 
chians." (Ibid,  II,  xxxi,  395).  Subsequently,  in  1870,  the 
conclusion  was  reached  that  "there exists  to  the  northwest 
of  Lake  Superior  an  extended  series  of  crystalline  schists 
unlike  the  Laurentian,  and  resembling  those  of  the  White 
Mountains."  (Ibid,  II,  1  85).  David  Dale  Owen  had 
noticed  and  described  in  1853,  similar  crystalline  rocks,  as 
seen  in  Iowa  and  Wisconsin. 

§  343.  Logan,  in  1806  pointed  a  similarity  between  the 
rocks  of  the  Hastings  series,  and  certain  strata  along  the 
eastern  base  of  the  Green  Mountains  in  Canada  and  Ver- 
mont, (§  331).  It  was  moreover  evident  that  these  lime- 
stones, slates  and  quartzites  of  central  Ontario  had  close 
resemblance  with  those  strata  in  western  New  England, 
which  Emmons  had  <nilled  the  Lower  Taconic  series  (§  104- 
105).  Isolated  areas  of  rocks  related  to  these,  both  geo- 
gnostically  and  minera logically,  are  found  in  several  parts 
of  eastern  North  America,  and  are  probably  portions  of  an 
ancient  formation,  once  widely  spread. 

Such  an  ar«3a  is  described  by  Emmons  as  occurring  at 
Camden  in  Maine,  where  the  Lower  Taconic  rocks,  having  tlie 
same  characters  as  in  Berkshire  county,  Massachusetts,  are 
fully  exposed,  with  a  moderate  nortliward  dip,  in  a  section 
showing  an  estimated  thickness  of  2000  feet.  The  quartzite, 
which  forms  the  lower  member,  is  there  divided  into 
two  pai'ts  ]\y  ii  mass  of  slates,  and  is  partly  conglomerate, 
whil(^  the  limestone,  with  a  thickness  of  two  hundred  and 
lifty  feet,  is  both  underlaid  and  overlaid,  by  slates,  de- 


! 


TACONIC   ROCKS   IN    NEW    BIIUNSWICK. 


E.    170 


of  an 


lug  at 
bgtlie 
ts,  are 
3ction 
Irtzito, 
into 
Icrate, 
|l  Jiiid 
de- 


scribed as  partly  silicious,  and  partly  talcose  or  magnesian, 
traversed  by  a  granitic  vein,  and  containing  in  some  parts 
imperfect  macles  and  staurolite  crystals.  A  mass  of  quartz- 
ose  conglomerate,  four  or  live  hundred  feet  thick,  belonging 
to  the  series,  and  including  pebbles  of  quartz  and  of  granite, 
apx^ears  as  an  isolated  hill,  named  Megunticook,  in  the 
vicinity,  and  rests  unconformably  upon  the  mica-schists  of 
the  region  which,  with  their  interstratilied  gneisses  and 
granitic  rocks,  are  by  Emmons  distinguished  as  Primary. 
The  limestones  of  Thomaston,  a  few  miles  distant  from 
Camden,  are  also  by  this  observer  declared  to  belong  to  the 
Lower  Taconic,  to  which  moreover  he  refers,  with  great 
probability,  many  of  the  silicious  and  argillaceous  schists 
of  this  part  of  Maine.  The  limestones  and  associated  rocks 
of  Cumberland,  Rhode  Island,  are  also  supposed  by  Em- 
mons to  belong  to  the  same  series.  (Agriculture  of  New 
York,  Vol.  I,  pages  97-101,  and  American  Geology,  Vol.  II, 
pages  20-22). 

§  344.  Farther  to  the  northeast,  along  the  Bay  of  Fun- 
dy  in  southern  New  Brunswick,  are  numerous  exposures 
of  rocks  having  close  resemblances  to  those  of  Camden. 
The  strata  are  much  disturbed  and  eroded,  but  are  seen 
at  several  points  along  the  coast,  as  at  Frye's  Island, 
L'Etang  Peninsula,  Pisarinco,  and  the  mouth  of  the  river 
St.  John.  At  this  last  locality  is  a  section  along  the  Green- 
Head  road,  on  the  right  bank  of  the  river,  described  in 
detail  by  Matthew  and  Baihsy,  in  the  report  of  the  geo- 
logical survey  of  Canada  for  1870  (page  38).  The  strata, 
with  a  general  southeast  dip  of  about  50°,  have  a  surface- 
measurement,  across  the  strike,  of  4,100  feet,  of  which 
1,500  are  limestones,  and  the  remainder  chiefly  quartzites, 
oftc^n  schistose,  with  argillaceous  and  somewhat  micaceous 
schists,  and  occasional  hornblendic  layers.  Considerable 
masses  of  conglomerate,  with  silicious  and  calcareous  peb- 
bles, are  also  included  in  the  series,  the  members  of  which 
are  not  improbably  repeated  by  dislocations.  The  lime- 
stones, of  which  there  api^ear  to  be  several  masses  two  or 
three  hundred  feet  in  breadth,  are  in  part  distinctly  crystal- 
line and  white,  or  banded  witli  blue  and  gray  colors,  and  in 


!■■' 


I;.  1' 


-f 


180  E. 


SPECIAL    UKPORT.      T.    STERRY   HUNT. 


part  finely  granular,  grayish,  schistose,  and  sometimes  con- 
cretionary in  structure.  They  are  frequently  magnesian, 
and  occasionally  contain  small  masses  of  pale  yellow  ser- 
pentine, and  a  silvery  white  mica.  Portions  of  the  lime- 
stone are  api)arently  colored  by  carbonaceous  matter,  and  a 
bed  of  impure  schistose  graphite,  which  is  wanting  in  the 
crystalline  aspect  of  the  Laurentian  gra|)liite,  is  mined  in 
these  rocks,  near  the  falls  nt  the  mouth  of  the  river  St. 
John.  These  limestones  have  lately  yielded  to  Dr.  Dawson 
the  remains  of  Eozooii  Canadense. 

§  345.  This  succession  of  crystalline  limestones,  quartzites 
and  slates,  is  clearly  older  than  the  wholly  uncrystalline 
sandstone  and  shales  of  Lower  Cambrian  (Menevian)  age, 
which,  with  their  characterisiic  fauna,  are  found  in  close 
proximity.  These  latter  strata  appear  to  be  in  part  made 
up  of  the  ruins  of  the  older  schists,  and  in  one  section  beds 
of  quartzite  and  conglomerate,  believed  to  belong  to  the 
limestone  series,  appear  betwe(?n  the  Menevian  slates  and  the 
underlying  Huronian  strata.  A  mile  or  two  away  however, 
the  limestone  series  is  seen  to  rest  upon  red  granitoid  gneiss- 
es, regarded  as  Laurentian,  and  has  itself  been  described,  in 
the  report  Just  mentioned,  as  an  upper  member  of  the  Lau- 
rentian series.  It  however  differs  widely  from  all  the  rocks 
of  this  series  and,  on  the  contrary,  presents  such  strong  re- 
semblances with  those  of  Hastings  county  that  the  writer, 
after  much  time  spent  in  examining  the  two  regions,  was 
led  to  refer  them  both  to  the  same  geological  horizon,  and 
to  express  the  opinion  that  they  are  identical  with  the  sim- 
ilar crystalline  limestones,  quartzites  and  slates  of  Berk- 
shire county,  Massachusetts,  and,  like  the  strata  of  Camden, 
belong  to  the  Lower  Taconic  series  of  Emmons.  (Proc. 
Bost.  Soc.  Nat.  Hist.,  April,  1875,  Vol.  XVII,  page  509). 

§  346.  When,  in  1870,  the  mica-schist  series  of  Lake 
Superior  was  compared  with  that  of  the  White  Mountains, 
the  similar  roclvs  previously  described  in  connection  with 
the  Hastings  series  (§  335)  were  naturally  included.  At  the 
same  time,  from  a  study  of  the  collections  and  the  descrip- 
tions of  Mr.  Alex.  Muri'ay,  then  in  the  writer's  hands,  it 
appeared  that  there  existed  in  Newfoundland,  between  the 


THE   MOXTALBAX   SERIES. 


E.    181 


Laiirentian  gneisses  and  the  fossil  if  erous  strata  of  Lower 
Cambrian  age,  a  series  of  several  thousand  feet  in  tlii(^lcness, 
whicli  included  in  its  lower  portion  mica-schists  and 
gneisses,  and  in  its  upper  portion  white  marbles,  limestones 
and  slates,  like  those  of  Hastings.  Regarding  these,  at  that 
time,  ad  making  but  a  single  group,  it  was  said:  "To  the 
whole  of  these  we  may  iDerliai:)3  give  the  provisional  name 
of  Ten-anovan,  in  allusion  to  the  name  of  Newfoundland."  ul 
(Amer.  Jour.  Sci.  II,  1.  87.)  '' 

§  0-47.  It  was  soon  apparent  that  this  was  a  hasty  gen- 
eralization, and  that  the  lower,  or  mica-schist  and  gneiss 
series,  was  very  distinct  from  the  great  limestone  and  slate 
series,  which  had  been  united  with  it.  In  two  [)apers  pub- 
lished in  1870,  the  name  of  Terranovan  was  cited  jis  a  pro- 
visional designation  for  the  gnessic  series  (Chem.  and  Geol. 
Essays,  pages  194,  275,  27C)  but  in  an  address  on  the  Geog- 
nosy of  the  xVppalachians  and  the  Origin  of  Crystalline 
Rocks,  delivered  before  the  American  Association  for  the 
Advancement  of  Science,  in  August  1871,  the  rocks  in 
question  were  designated  simply  as  the  White  Mountain 
series,  while  the  more  recent  limestone  series,  not  being 
recognized  in  the  line  of  section  there  described,  was  not 
considered.     (Ibid,  page  244). 

§  ;;y8.  It  was  however  desirable  to  have  a  specilic  desig- 
nation for  this  great  series  of  mica-schist  and  gneiss,  whi(;h 
is  so  conspicuous  in  American  g(M)logy,  and  tliat  of  INIontal- 
ban  (fi'om  the  latinized  name?  of  the  Wiiite  Mountains)  sug- 
gested itself.  This  name,  in  tht.'  autumn  of  1871,  was  com- 
municated by  the  writer  to  his  friend  and  correspondent.  Dr. 
GTiimbel,  director  of  the  geological  survey  of  Jjavaria.  This 
eminent  geologist  soon  after  joublished  an  extended  review 
and  exposition  of  the  essay  above  referred  to,  so  far  as  it 
regarded  the  succession  and  the  genesis  of  crystalline 
stratified  I'ocks.  Therein,  while  giving  the  characteristics 
of  the  White  Mountain  series,  he  adopted  the  writt;r  s 
suggestion  that  it  ''might  be  called  the  Montalban  system." 
(iVrv  Aiislan(h  Dec.  2i),  1871,  page  1228;  see  also  the  same 
journal  for  1872,  pages  231  and  252). 

§  349.     The  question  of  the  geological  age  of  the  strata 


m 


182  E. 


SPECIAL    REPORT.      T.    STERRY    HUNT. 


f: 


I: 


I! 


I  ■ 


both  of  the  White  Mountains  and  the  Green  Mountains, 
has  been  discussed  in  preceding  chapters,  where  we  have 
seen  that  these  rocks,  called  Primitive  or  Primary  by  Ea- 
ton, Emmons  and  Jackson,  were  by  Mather  and  the  Messrs. 
Rogers  regarded  as  metamorphosed  or  altered  paleozoic  for- 
mations (§80-82,  122,  123).  The  latter  view,  as  has  been 
shown,  was  taken  up  by  Logan,  who  suggested  that  tlie 
rocks  of  the  White  Mountains  were  probably  altered  Devon- 
ian strata,  while  those  of  the  Notre  Dame  range  in  east- 
ern Canada,  the  prolongation  of  the  Green  Mountains  from 
Vermont,  believed  to  be  stratigraphically  inferior  to  the 
White  Mountain  rocks,  were  regarded,  in  accordance  with 
the  opinion  of  Mather,  as  the  altered  representatives  of  the 
Hudson  River  group,  with  the  probable  addition  of  the 
Shawangunk  or  Oneida  formation.  (§  171-174).  The  Hudson 
River  group  was  then  regarded  as  equivalent  to  the  Lo- 
raine  shales,  so  that  the  crystalline  schists  of  the  Green 
Mountains  were  supposed  to  belong  to  a  horizon  above  the 
Trenton  limestone,  and  to  be  the  stratigraphical  equiva- 
lents of  the  uncrystalline  Graywacke  formation  found 
along  their  northwestern  border.  This  view,  enunciated 
by  Logan  in  1849,  was  still  maintained  in  1855  (§  190). 

§  350.  The  paleontological  researches  by  which  the  geo- 
logical survey  of  Canada  was  led  to  conclude  that  these 
uncrystalline  strata  of  the  Hudson  River  group,  were 
really  older  instead  of  younger  than  the  Trenton  limestone, 
and  identical  with  the  Upper  Taconic  series  of  Emmons, 
have  l)e(^n  already  set  forth,  and  the  adoption  for  them  of 
the  name  of  tlie  Quebec  group  is  noticed  in  §  201  ;  while  in 
^  231,  it  has  been  shown  that  these  strata  were  supposed 
to  be  arranged  in  a  great  synclinal,  traced  from  Lake  Cham- 
plain  to  Quel)ec,  the  crystalline  rocks  forming  the  hills 
of  the  Green  Mountain  range  being  described  as  occupy- 
ing a  second  and  a  third  synclinal  to  the  southeast  of  the 
first  named.  The  geography  of  these  crystnlline  rocks  is 
set  forth  in  ^  IGG,  107,  and  their  lithological  characters  are 
briefly  descriltcd  in  ^  172. 

§351.  The  geographical  distribution  of  thfse  three  syn- 
clinals is  given  in  the  Geology  of  Canada,  1863,  (pages  709, 


THE  GREEN   MOUNTAIN   ROCKS. 


E.    183 


ipy- 

tllQ 

:s  is 
are 


ijn- 
709, 


710)  wliere  it  is  said  that  the  strata  tliroughout  tlie  region 
in  question  are  in  long  narrow  parallel  folds,  "with  many- 
overturn  dips.  This  latter  circumstance  makes  it  diilicult 
to  detennine  -which  of  these  folds  are  synclinal  and  which 
anticlinal,  inasmuch  as  the  outcrop  in  both  cases  presents 
a  similar  arrangement.  The  weight  of  evidence  however 
at  present,  goes  to  show  that  the  strata  dij)  towards  the 
centre  of  the  areas  about  to  be  described,  and  they  will 
therefore  be  designated  as  synclinals." 

A  more  detailed  account  of  the  rocks  in  these  three  suj)- 
posed  synclinals  will  be  found  in  the  report  for  18G3-G0, 
pages  31-44.  Having  therein,  for  the  first  time  divided  the 
fosiliferous  strata  of  the  so-called  Queljec  gi'oup,  as  displayed 
in  the  northwest  synclinal,  into  three  parts, — designated,  in 
ascending  order,  as  the  Levis,  Lauzon  and  Sillery  divisions, 
an  attempt  was  now  made  to  extend  these  distinctions  to 
the  highly  inclined  and  often  inverted  crystalline  strata  of 
the  Green  Mountain  range,  described  as  belonging  to  the 
second  and  third  synclinals. 

§  352.  It  was  assumed  that  certain  black  argillites,  some- 
times carbonaceous  or  plumbaginous,  with  occasional  lime- 
stones, represent,  in  these  synclinals,  the  Jjevis  division, 
while  the  Lauzon  and  Sillery,  it  was  said,  "may  be  con- 
sidered as  a  lower  and  upper  copper-l)earing  formation."' 
The  interbedded  sulphuretted  ores  of  copper,  frequently 
found,  with  iron,  chrome  and  nickel  ores,  in  these  crys- 
talline rocks,  are  chielly  ('(jiilined  to  belts  characterized 
by  the  presence  of  serpentine,  diallage,  steatite,  chlorite, 
magnesite  and  dolomite,  and  from  the  prevalence  of  mag- 
nesia in  all  of  tliese,  were  spoken  in  the  rejKjrt  as  the  "mag- 
nesian  bands  ;"  the  other  rocks  of  the  series  being  quartz- 
ose,  feldspathic  and  epidotic  strata,  with  argilites  and 
certain  hydrous  mica-schists,  often  designated  nacreous 
slates.  Of  two  very  similar  magnesian  bands,  one  Avas  sup- 
posed to  be  included  in  the  base  of  the  Lauzon,  and  the 
other  in  the  base  of  the  Sillery  division.  To  tlie  Lauzon  di- 
vision, which  thus  separated  the  two,  was  assigned  a  very 
variable  thickness.  "  In  some  parts  the  whole  mass  appears 
to  be  scarcely  more  than  100  feet  wide,  while  in  oth«irs,  it 


i 
■ 


A 


li 


t  ;j  - 

1 1 '( I 
Hi 


M 


1 
1 

I 


f 


i'    ! 


I 


184  E.      SPECIAL   BEPORT.      T.    STERRY   HUNT,  1875. 

may  reach  2000  or  even  nearly  4000  feet."  This  supposi- 
tion was  rendered  necessary  by  the  attempt  to  establish  in 
this  region  the  existence  of  two  distinct  magnesian  bands, 
which  like  the  whole  attempt  to  correlate  this  cystalline 
series  with  the  nncrystalline  Cambrian  rocks  adjacent,  has 
since  been  shown  to  be  fallacious. 

It  is  to  be  remarked  that  the  report  of  1800,  quoted 
above,  although  bearing  the  name  of  Mr.  Richardson,  and 
embodying  his  field-notes,  was  really  the  work  of  Sir  Wil- 
liam Logan,  and  was  the  elaboration  of  his  own  previously 
expressed  views  of  the  geological  structure  of  the  region  in 
question. 

§  S.OS.  In  order  to  understand  aright  the  steps  by  which 
a  more  correct  view  of  the  geological  horizon  of  the  crystal- 
line rocks  of  the  Green  Mountain  range  was  attained,  it  will 
be  necessary  to  recall  the  fact  that  neither  the  hypothesis 
\  of  Mather,  nor  that  put  forth  by  Logan  subsequent  to 
:18G1,  admitted  the  existence  in  Eastern  North  America  of 
jany  rock-formation  between  the  gneiss  of  the  Adirondacks, 
and  the  Potsdam  sandstone,  which  was  regarded  as  the 
base  of  the  New  York  x)aleozoic  series.  The  whole  of  the 
crystalline  strata  of  the  Atlantic  belt,  exce^^t  so  far  as  they 
might  belong  to  that  ancient  gneiss,  were  sujiposed  to  have 
resulted  from  the  alteration  of  the  strata  of  the  New  York 
paleozoic  series,  of  which  they  were  believed  to  be  the  east- 
ward extension.  The  existence  of  the  great  Iluronian 
group  in  a  position  between  the  paleozoic  and  the  Primary 
gneiss,  had,  it  is  true  been  recognized  on  the  upj)er  Ottawa, 
and  on  lakes  Huron  and  Superior,  but  was  not  admitted  by 
Logan  as  a  possible  factor  in  the  geology  of  the  Atlantic 
belt. 

§  354.  As  early  as  1849,  Logan  had  found  in  the  vicinity 
of  Lake  Temiscouata,  near  the  head-waters  of  the  river  St. 
John,  unconformably  overlaid  by  the  Silurian  strata  of  the 
Gaspd  seiies  (§  175)  an  older  series  of  sandstones  and  con- 
glomerates, in  which  were  included  pebbles  of  serpentine 
and  other  crystalline  rocks,  evidently  derived  from  the 
Green  Mountain  range.  From  the  geognostical  relations  of 
these  older  detrital  rocks,  they  seemed  to  belong  to  the 


THE  GREEN   MOUNTAIN    KOCKS. 


E.    185 


Sillery  formation,  of  which  they  had  also  the  lithological 
characters  ;  but  since  this  conclusion  was  not  to  be  recon- 
ciled with  the  theory  which  made  the  ci-ystalline  rocks 
from  which  the  pebbles  had  been  derived,  a  portion  of 
the  Sillery  formation,  Logan  was  led  to  refer  these  sand- 
stones and  conglomerates  to  some  unknown  formation 
older  than  the  Gaspd  series,  though  newer  than  the  Quebec 
group.  (Report  for  1849,  pages  50-64,  and  Geology  of 
Canada,  18(5;},  pages  423,  426,  427). 

§  355.  In  1856  however,  the  writer  desciibed  the  exist- 
ence in  the  Levis  division  of  the  Quebec  group,  at  Point 
Levis,  of  adolomitic  conglomerate,  holding  pebbles  of  green- 
ish and  i)urplish  slates,  sometimes  cliloritic,  (§  207.) 
Later,  in  1861,  he  described  the  occurrence  in  the  Pots- 
dam sandstone  of  Hemmingford,  near  the  outlet  of  Lake 
Champlain,  of  large  pebbles  of  similar  green  and  black 
slate.  (Amer.  Jour,  of  Science  11,  xxi,  404).  The  frag- 
ments of  slates,  from  both  of  these  localities,  were  wholly 
unlike  anything  to  be  found  in  the  Laurentian,  and  on 
the  contrary  resembled  those  of  the  Green  Mountain  range, 
suggesting  irresistibly  that  these  were  more  ancient  than 
either  the  Quebec  group  or  the  Potsdam  sandstone. 

§  356.  Eaton,  in  1832,  had  taught  that  the  talcose,  chlo- 
ritic  and  micaceous  schists,  with  tin-  hornblende  rocks  and 
gneisses  of  New  England,  belonged,  like  the  gneisses  of  the 
Adirondacks,  to  the  Primitive  series,  (§  50)  and  in  this  was 
followed  by  Emmons,  who  included  the  above  rocks,  to- 
gether with  what  he  called  "laminated  serpentines,"  steat- 
ites, and  certain  clay-slates,  in  the  Primary,  or,  as  he  sub- 
sequently called  them,  from  certain  theoretical  views  as  to 
their  origin,  the  "laminated  pyrocrystalliH*^  rocks."  To  this 
class  he  referred  the  crystalline  schists  both  of  th<^  Green 
Mountains  and  the  White  jSrountains,  which  he  placed  not 
only  beneath  the  New  York  paleozoic,  but  beneath  the  Ta- 
conic  series  (American  Geology,  I,  page  43  et  seq.). 

§  357.  In  1802  Mr.  Thomas  Macfarlano  who  was  familiar 
with  the  geology  of  Norway,  and  had  examined  in  the  lield, 
the  crystalline  rocks  of  the  Green  Mountains  in  Canada, 
and  those  of  the  Iluronian  series,  as  seen  on  Lake  Huron, 


m 


^li 


mi 


.  ) 


18«    E.      HI'KCIAL   REPORT.      T.  STERUY  HUNT,  ISTO. 

compared  both  of  these  with  the  Primitive  scliist  formation, 
which,  in  Norway,  is  found  between  the  Primitive  gneiss 
(§  309)  and  the  lower  paleozoic  strata.  This  intermediate 
series  has  been  by  Scandinavian  geologists  divided  into 
a  lower  and  an  npper  group,  and  Macfarlane,  while  com- 
])aring  the  massive  greenstones,  quartzites,  conglomerates 
and  limestones,  which  he  had  seen  on  Ljike  Huron,  with 
the  lower,  suggested  that  the  u])per  and  more  schistose  div- 
ision was  represented  in  the  crystalline  roc^ks  of  the  Green 
Mountains.  Bigsby,  who  had  been,  as  we  have  seen,  the 
first  to  study  and  describe  the  Iluronian  schists,  in  the  fol- 
lowing year,  and  inJ  3pendently,  compared  these  to  the 
Primitive  schist  foi-mation  of  Norway.  (Canadian  Natural- 
ist, VII,  125;  Qiuir.  Jour.  Geol.  Soc.  XIX,  3G,  and  Chem. 
and  Geol.  Essays,  29,  2G9).  He  did  not  insist  upon  the 
distinction  made  by  Macfarlane,  and  in  fact  both  the  mas- 
sive and  schistose  divisions  of  the  Primitive  schists,  are  well 
represented  in  the  Iluronian  region  of  the  great  lakes.  The 
resemblances  between  the  argillites,  white  nacreous  schists, 
and  greenish  compact  epidotic  rocks  of  the  Slate  Islands  in 
Lake  Superior,  and  certain  strata  of  the  Green  Mountains 
in  Canada,  were  pointed  out  by  the  writer  in  the  Geology 
of  Canada  (page  705). 

§  358.  The  conclusions  of  Macfarlane  (though  not  the 
later  one  of  Bigsby)  appeared  while  the  volume  just  men- 
tioned was  in  press,  and  were  noticed  therein,  on  pages  590 
and  C16.  As  regards  the  resemblances  to  the  rocks  of  the 
Green  Mountains,  allusion  was  then  made  to  the  opinion 
which  had  ))een  expressed  by  Keilhau,  that  there  is  in 
Norway  a  gradual  passage  from  the  Primitive  schists  to 
the  lower  fossiliferous  rocks. 

A  like  view  was  held  by  H.  D.  Rogers  with  I'egard  to 
the  similai'  rocks  designated  by  him  as  the  Primal  crystal- 
line (or  Azoic)  schists  in  Pennsylvania.  These  he  declared, 
in  1858,  to  constitute  ''apparently  a  portion  of  the  Paleo- 
zoic system"'  which,  in  its  downward  extension,  was  sup- 
posed by  him  to  graduate  into  these  crystalline  schists. 
Above  the  latter,  which  rested  upon  the  Primary  or  Hypo- 
zoic  gneisses,  Rogers  placed  two  divisions,  called  the  Primal 


CRYSTALLINE  SCHISTS   OF  OREAT   BUITAIX.      E.  187 


>t  the 
men- 
!S  590 
.f  the 
hinion 
is  in 
Ists  to 

Lid  to 
Jystal- 
llarecl, 

*aleo- 
snx)- 

[hists. 

[lypo- 

fiinial 


conglomerate  and  the  Primnl  older  slates,  surreedino;  which, 
in  ascending  order,  was  the  Primal  white  sandstone,  re- 
garded by  him  as  the  equivalent  of  the  Potsdam  sandstone, 
the  base  of  the  New  York  paleozoic  series  (J  4-7).  Thus 
the  crystalline  schists  between  the  ancient  gneiss  and  the 
Potsdam,  which,  in  1840,  had  been  by  Rogers  included  in 
the  Primary  (§  C2)  were  now,  in  1808,  called  paleozoic, 
though  still  assigned  to  the  s;ime  geological  horizon  as  be- 
fore. In  fact,  while  seeming  to  accept  the  hypothesis  of 
a  metamorphic  jiah^ozoic  series,  Rogers  novNr  held  substan- 
tially the  views  of  Eaton  and  of  Emmons  as  to  the  existence 
of  a  gi'eat  crystalline  series  lying  above  the  older  gneiss, 
but  below  the  Potsdam.  The  similar  crystalline  rocks  of 
the  Green  Mountain  range,  on  the  contrary,  were,  accord- 
ing to  Logan,  the  metamorphosed  strata  of  the  Quebec 
group,  and  belonged  to  a  horizon  above  the  Potsdam  sand- 
stone. 

§  859.  The  crystalline  schists  which  in  Caernarvonshire 
and  Anglesea  are  found  at  the  base  of  the  sedimentary 
series,  were  at  iirst,  in  1835,  included  by  Sedgwick  with  the 
latter,  as  a  lower  member  of  his  Cambrian  system.  In 
1838,  however,  he  separated  these  crystalline  rocks  from  the 
Cambrian,  and  henceforth  regarded  them  as  belonging  to  an 
older  series,  a  view  which  was  shared  by  John  Phillips, 
(Chem.  and  Geol.  Essays,  pages  353,  383).  Murcjhison,  fol- 
lowing Delabeche,  called  them  altered  Cambrian,  and  havirig 
suggested  to  Logan  that  the  Huronian  series  of  Canada 
might  be  the  equivalent  of  these  crystalline  strata  of  Caer- 
narvonshire and  Anglesea,  the  name  of  Cambrian  was,  for  a 
time,  occasionally  used  by  the  geological  survey  as  synon- 
ymous with  Huronian,  until  Bigsby,  in  18G3,  in  a  paper 
already  cited  (§  145)  showed  that  the  only  strata  to  which 
the  name  of  Cambrian  clearly  belonged,  were  uncrystalline 
sediments,  and  that  the  Huronian  rocks  were  to  be  referred 
to  a  more  ancient  series,  the  Primitive  schists  of  Norway. 
Nicol  has  maintained,  in  opposition  to  Murchison  and  Giekie, 
similar  views  with  regard  to  the  rocks  of  the  Scottish  High- 
lands which,  according  to  the  writer's  observations,  are 


ni 


I 


nil 


} 


y 


I!  i 


'i'  ! 
■;:  I 


f$h 


188  E.      SPECIAL    RKPORT.      T.  STERllY   HUNT,  1875. 

itlontical  with  tlio  primitive  crystalline  schists  of  North 
America.     (Ibid.,  pages  271,  272). 

§  360.  Tlie  writer,  from  his  studies  of  these  crystalline 
rocks  of  Wales  expressed,  in  1871,  the  opinion  that  they  are 
identical  with  those  of  the  Green  Mountain  or  Iluronian 
series,  (Ibid.,  pages  2G9,  353,  383).  These  rocks  as  dis- 
played in  Caernarv(msliiro,  and  similar  ones  near  St.  David's 
in  South  Wnles,  hith«n-to  regarded  by  the  geological  survey 
of  Great  Britain  as  in  part  altered  Cambrian,  and  in  part 
eruptive,  are  now  shown  by  Hicks  to  lie  uncomformably  be- 
neatli  the  Cambrian,  and  are  referred  by  him  to  a  lower 
group  named  Diraetian,  and  an  upper  called  Pebidian. 
According  to  McKenna  Hughes  however,  these  two  consti- 
tute but  a  single  conformable  pre-Cambrian  series,  the  litho- 
logical  descriptions  of  which  seem  to  show  that,  like  the 
rocks  of  Anglesea,  (already  classed  with  them  by  Sedg- 
wick,  and  by  the  writer,)  they  also  bekmg  to  the  Iluronian 
series.     (Proc.  Geol.  Soc,  London,  Nov.  21,  1877.) 

§  301.  In  a  paper  on  the  Geology  of  St.  John  County, 
New  Brunswick,  published  in  the  Canadian  Naturalist  in 
18(53,  and  re-printed  in  part  in  the  geological  report  of 
Canada  for  1870-71,  page  23,  Mr.  George  F.  Matthew  de- 
scribed, under  the  name  of  the  Coldbrook  group,  a  great 
mass  of  crystalline  strata  found  in  southern  New  Bruns- 
wi(4v,  to  the  east  of  the  river  St.  John.  These  rocks  repose 
on  the  Laurentian,  and  underlie  unconformabh'  the  uncrys- 
talline  Lower  Cambrian  slates  of  the  city  of  St.  John,  which 
include,  near  their  base,  conglomerates  holding  fragments 
of  the  Coldbrook  group.  From  this,  and  from  their  litlio- 
logical  characters,  these  older  rocks  were,  by  Matthew,  re- 
ferred soon  after  to  the  Iluronian  series.  (Quar.  Jour. 
Geol.  Soc.  Nov.,  180.")).  They  have  since  been  found  to  rest 
unconformably  upon  the  Laurentian,  i)ebbles  of  which  are 
contained  in  the  conglomerates  of  the  Coldbrook  group. 

§  3G2.  In  the  paper  which  contained  his  account  of  the 
Coldbrook  group,  in  1803,  Mr.  Matthew  described  a  second 
belt  of  crystalline  rocks  similar  to  these,  to  which  he  gave 
the  name  of  the  Bloomsburj^  group.  These,  ajiparentlj'- 
resting  upon  the  Menevian,  and  conformably  overlaid  by 


great 
runs- 
epose 
ncrys- 
whicli 
irients 
itlio- 
r,  re- 
Jour. 
0  rest 
U  are 
ip. 
t)f  the 
econd 
3  gave 
ently 
id  by 


IIUIiONlAN    li(J(,KS    1\    \E\V    K\(JLAN'D. 


E.    180 


the  fossil iferous  Devonian  sandstones  of  8t.  J(din,  were,  at 
tliat  time,  called  by  him  altered  Devonian  strata.  In 
18(50  and  1870,  however,  the  writer  devoted  some  weeks, 
in  connection  with  Prol".  L.  W.  I3ailevand  Mr.  M;itrliew.  to 
tln!  investigation  of  thegeology  of  southern  Xcw  Hninswick, 
when  it  appeared  that  the  J31oomsbury  rocks  wern  but  a 
lepetition  of  the  Coldbrook  group  on  the  opposite  si(h;  of  a 
closely  folded  synclinal  holding  Lower  Cambrian  sediments. 
Accordingly,  in  the  gecdogical  report  of  the  gentlemen  Just 
named,  both  of  these  belts  were  designated  as  Ilui-onian  ;  in 
which  were  now  also  included  two  other  sulidivisions  of 
crystalline  rocks  found  in  that  region,  and  previously 
designated  the  Coastal  and  Kingston  gi'oups.  (Repoi't  of 
Geol.  Sur.,  1870-71,  pages  27,  00,  04). 

§  303.  These  lliironian  rocks  were  traced  in  1809  and  1870 
along  the  southern  coast  of  New  Brunswick,  from  the  liead 
of  the  Bay  of  Fundy  to  the  conlines  of  Maine,  as  was  stated 
by  the  writer  in  July,  1870,  when  these  rocks,  "called 
Cambrian  and  Iluronian  by  Mr.  Matthew,"  and  character- 
ized by  the  oc(!urrence  of  diorites  and  quartziforous  feld- 
spar-porphyries, were  said  to  occur  in  Eastport,  Maine,  and 
in  Newbury,  Salem,  Lynn,  and  Marblehead,  Massachusetts. 
(Amer.  Jour.  Science,  II,  1,  89).  In  October  of  the  same 
year,  after  a  further  study  of  these  rocks  in  the  vi(nnity  of 
Boston,  and  at  New^port,  they  were  described  as  follows  by 
the  writer  in  the  Proceedings  of  the  Boston  Society  of 
Natural  History,  (vol.  XIV,  pages  45,  40). 

§  304.  The  crystalline  stratified  rocks  in  question,  it  was 
said,  "may  be  sei)arated  lit hologically  into  two  divisions,  the 
first  being  the  quartzo-feldspathic  rocks.  Among  these  are 
included  the  felsite-porphyries  of  Lynn,  Saugus  and  ]\Iar- 
blehead,  with  their  associated  non-porphyritic  and  jasper- 
like varieties,  the  compact  feldspar  of  Hitchcock,  who  has 
well  described  these  rocks  in  the  C+eology  of  Massachusetts, 
pages  004,  007.  Associated  with  them  is  a  granular 
quartzo  feldspathic  rock,  which  is  often  itself  porphyritic, 
with  feldspar  crystals,  and  sometimes  appears  as  a  fine- 
grained syenitic  or  gneissoid  rock,  often  distinctly  strati- 
fied.    This  has  been  described  by  Hitchcock  as  intermedi- 


■1^ 


■ 


190  E.     spp:cial  report,     t.  steury  hunt,  1875. 

ate  between  porphyry  unci  syenite  ;  his  syenites  with  a 
nearly  or  quite  compact  feldspar  base,  and  some  of  his  por- 
phyritic  syenites,  (Ibid.,  pp.  008,  000)  will  probably  be  found 
to  belong  to  these  granular  euritcs,  which  I  connect  with  the 
porphyries.  These  rocks  are  seen  intimately  associated  wi  th 
the  porphyry  on  Marblehead  Neck  ;  also  in  Marblehead,  and 
underlying  the  argillites  of  Braintree  and  Weymouth." 

§  305.  The  second  division  of  these  rocks  "  includes  a  se- 
ries of  dioritic  and  chloritic  rocks,  generally  greenish  in 
color,  sometimes  schijtose,  and  frequently  amygdaloidal. 
They  often  contain  epidote,  quartz  and  calcite,  and  occa- 
sionally actinolite,  amianthus,  scaly  chlorite  and  copi)er- 
pyrites.  This  series  holds  "  *  serjtentine  in  Lynn- 
field,  where  bedded  serpentines,  dipping  at  a  high  angle 
to  the  northwest  occur,  apparently  in  the  strike  of  these 
dioritic  and  epidotic  rocks,  which  include  the  green- 
stones of  Dr.  Hitchcock,  described  by  him  as  occasionally 
schistose,  and  passing  into  hornblende  slate,  (Ibid.  pp.  548, 
647) ;  and  also  his  varioloid  wacke,  under  which  name  he 
describes  the  green  and  chocolate-colored  amygdaloidal  ep- 
idotic and  (;hloritic  rocks  of  Brighton,  and  the  somewhat 
similar  rocks  of  Saugus,  which  are  seen  within  a  few  hun- 
dred feet  to  the  northwest  of  the  limit  of  the  red  jaspery 
petrosilex.  This  series  of  magnesian  rocks  is  apparently 
identical  with  that  which  occurs  with  dolomite  and  massive 
dark-colored  serpentines,  in  the  city  of  Newport,  Rhode 
Island,  wliere  the  beds  have  also  a  high  dip  to  the  north- 
west." 

§300.  "A  similar  series  of  strata  is  largely  displayed 
on  the  islands,  and  along  tlie  shores  of  Passamaquaddy 
Bay.  Tlie  dioritic  and  chloritic  beds  towards  their  base  are 
there  inters tratified  with  red  felsite-porphyries  '■'  *  *  * 
which,  associated  with  granular  eurites,  form  great  masses 
in  that  region.  I  regard  these  two  types  of  ro(;ks  as  form- 
ing parts  of  one  ancient  crystalline  series,  which  is  largely 
developed  in  the  vicinity  of  Boston,  and  may  be  traced  at 
intervals  from  Newport  to  the  Bay  of  Pundy,  and  beyond. 
To  this  same  series  I  refer  the  great  range  of  gneiss  ic  and 
dioritic  rocks,  with  serpentines,  chloritic,  talcose  and  epi- 


IIUKONIAN   K0CK8   IN   NEW   ENGLAND. 


E.  191 


these 


dotic  schists,  which  stretches  through  western  New  Eng- 
land"— that  is  to  say  the  Green  Mountain  range. 

§  307.  These  rocks  were  then  described  as  ' '  penetrated 
by  intrusive  granites,  generally  niore  or  less  hornblendic — 
the  syenites  of  Hitchcock  and  others.  They  often  contain 
two  feldspars,  as  in  the  well-marked  granite  of  Newport, 
Rhode  Island,  wliich  there  cuts  the  greenish  dioritic  and 
sometimes  amygdaloidal  rocks. ' '  The  granites  of  Cape  Ann 
and  Quincy  are  there  said  to  belong  probably  to  this  class, 
besides  which  examples  are  seen  "at  Stoneham  and  in 
Marblehead,  where  they  intersect  the  greenish  chloritic 
rocks,  and  on  Marblehead  Neck,  where  they  are  erupted 
among  the  felsite-porphyries." 

The  crystalline  rocks  of  this  ancient  series  were  shown  to 
be  overlaid  by  the  uncrystalline  sandstones,  conglomerates 
and  argillites,  including  those  which  at  Braintree  hold  a 
Lower  Cambrian  fauna,  and  rest  upon  the  folsite-porphyry. 

§  368.  Tlie  feldspar-porphyries  above  described  were  by 
the  late  Dr.  Hitchcock  in  1844,  classed  among  unstratilied 
rocks,  which  had  "once  been  melted."  In  tliis  class  also 
he  placed  the  whole  of  the  so-called  syenites  and  green- 
stones, which  were  made  by  him  to  include,  besides  truly 
eruptive  masses,  many  indigenous  rocks.  The  serpentines 
and  amygdaloids  were,  however,  correctly  described  as 
stratified  rocks. 

Another  type  of  rocks,  apparently  distinct  from  the 
Huronian  series,  and  occupying  a  small  area  on  Marblehead 
Neck,  was  described  in  the  above  pages  as  thin-bedded 
quartzites,  holding  dark  micaceous  layers,  and  becoming 
gneissoid  in  aspect.  Tiiese,  which  were  supposed  to  be 
newer  strata  than  the  Huronian,  are  also  cut  by  intrusive 
granites,  which,  in  their  turn,  are  intersected  by  eruptive 
greenstones,  having  a  genend  resemblance  to  certain  in- 
digenous rocks  of  the  ancient  series. 

§  309.  The  petrosilex  rocks  of  the  above  series  were 
further  described  in  February,  1870,  in  the  following  lan- 
guage: "Felsites  and  felsite-porphyries  are  well  known 
in  eastern  Massac^husetts,  *  *  *         j^j^j  jxvav 

be  traced  from  Machias  and  Eastport  in  Maine,  along  the 


n 


f.  -I 


ty 


U 


!!l 


192  E.     SPECIAL  liEPoirr.     t.  steuhy  iii^n't,  ISTo. 

southern  coast  of  New  Brunswick,  to  the  head  of  the  Bay 
of  Fundy,  with  great  uniformity  of  type,  though  in  every 
phice  subject  to  considerable  variations,  from  a  compact 
jasper-lilve  rock  to  more  or  less  coarsely  granular  varieties, 
all  of  Avhich  are  often  porphyritic  from  feldspar  crystals, 
and  sometimes  include  grains  or  crystals  of  quartz.  The 
colors  of  these  rocks  are  generally  some  shade  of  red,  vary- 
ing from  tiesh-red  to  purjole  ;  pale  yelhnv,  gray,  greenish 
and  even  black  varieties  are  however  occasionally  met  Avith. 
These  rocks  are.  throughout  this  region,  distinctly  strati- 
fied, Jind  are  closely  associated  with  dioritic,  chloritic  and 
ei:)id()tic  strata.  They  apparently  belong,  like  these,  to  the 
great  lluronian  system."  (Amer.  Jour.  Science,  III,  i,  84). 
§  870.  The  composition  of  these  rocks  is  shown  by  the  fol- 
lowing hitherto  unpublished  analyses  of  three  typical  spe- 
cimens, collected  by  the  writer,  which  were  made  by  a 
former  assistant,  Mr.  Gordon  Broom(\  I.  was  a  pale  red 
compact  variety,  with  feldsjiar  crystals,  and  had  l)een  de- 
scribed as  a  "porphyritic  slaty  quartzite,"  from  the  Cold- 
brook  group  iif'nr  St.  John,  Xew  Brunswick;  II.  was  a 
similar,  but  darker  red  variety  from  the  same  vicinity  ;  III. 
was  a  pur])lish-ied  line  grained  and  homogeneous  variety 
from  Newl)ury,  Massachusetts.  The  analyses  were  made 
tlie  aid  of  lluorhydric  acid,  and  the  silica  determined  by 
difference  : 


i   1 


l| 


1 

I. 

II. 

in. 

Silica 

81 .00 
7.43 
2.20 
1.43 

.71 
4.04 
1.72 

.21 

79.82 
8.87 
3.80 
.01 
1.83 
3.80 
1.58 
.14 

79.03 

0.07 

2.87 

.20 

.01 

f)  10 

1.45 

.47 

1 

Aliiiiiiiiii 

FcMTio  oxyd, 

Tjiiiio, 

Mii'^nosia.                                    ....        ... 

I'otiisli, 

Soda.                                                 

Volatile) 

Spocitic  emvitv 

100.00 

100.00 

100.00 

2.041 

2.000 

2. 028 

Their  chemical  composition  indicates  that  these  rocks  are 
composed  chielly  of  orthoclase  and   quartz,  a  conclusion 


HUUONIAN    ROCKS   JX    PENXSYLVANIA. 


E.  103 


wliich  is  confirmed  by  the  microscopic  study  of  the  com- 
pact or  crypto-crystalline  varieties. 

§  371.  It  was,  as  we  have  seen  in  1870,  that  the  Hnronian 
rocl^s  of  tlie  Atlantic  coast  were  declared  to  be  the  equiva- 
lents of  the  Green  Mountain  series.  In  the  writer's  address 
to  the  American  Association  for  the  Advancement  of  Science 
in  August,  1871,  tliis  view  was  developed  more  at  lencth, 
and  an  attempt  was  made  to  trace,  from  the  facts  then 
known,  this  Green  Mountain  or  Iluronian  series,  from  East- 
ern Canada  through  New  England  into  Pennsylvania,  and 
thence  into  North  and  South  Carolina.  (Chem.  and  Geol. 
Essays,  pages  243-250). 

In  187i),  while  examining  the  South  Mountain  to  the  west 
of  Gettysburg,  in  Pennsylvania,  he  discovered  a  remarka- 
ble and  hitherto  unrecognized  area  of  the  Iluronian  series, 
characterized  by  a  great  development  of  the  petrosilex-por- 
phyry,  which  was  thus  described  in  August,  1870:  "There 
is  here  found  a  great  breadth  of  this  rock,  distinctly  bedded, 
presenting  different  varieties,  and  alternating  withdioi-itic  or 
diabasic,  epidotic  and  chloritic  rocks,  and  with  ai-gillites,  in 
which  are  sometimes  included  thin  beds  of  the  j^etrosilex ;  the 
strata  generally  dipping  at  high  angles  to  the  southeast." 
These  were  then  compared  with  the  similar  strata  along  the 
Atlantic  coast,  from  Rliode  Island  to  New  Brunswick,  "in- 
terstratified,  as  in  the  South  Mountain,  with  rocks  having 
the  characters  of  the  Iluronian  series,  to  which  gietit  divi- 
sion I  have  provisionally  referred  these  bedded  ix'ti-osilex 
rocks,  with  the  suggestion  that  they  probably  occupy  a. 
positi(m  near  the  base  of  the  series."  (Proc.  Anier.  Assoc. 
Ad  van.  Science,  1870,  pp.  211,  212.) 

^  372.  These  rocks  were  then  declared  to  be  identical  in 
lithological  characters  with  the  hallellinta.  or  stratified 
tlint-i'ock,  of  the  Swedish  geologists,  which  is  by  them  as- 
signed to  a  horizrm  just  above  the  more  ancient  or  Primitive 
gneiss,  and  is  important  as  including  in  Noi-way  the  most 
('(msidei'able  deposits  of  crystalline  iron  ores.  These  same 
rocks  are  met  with  in  various  localities  in  the  Huronian  se- 
ries, (m  the  upper  lakes,  and  are  well  displayed,  as  oljserved 
by  the  writer,  in  a  small  island  lying  a  little  to  the  south 

[E.  13.J 


I 


:4 


F 


104  E.       SPECIAL   REPORT.      T.  STERRY  HUNT,  1875, 

of  St.  Ignace  island,  and  for  some  distance  along  the  shore 
of  the  adjacent  mainland,  to  the  southwest. 

§  373  In  the  same  paper  these  petrosilex  rocks  are  com- 
pared with  the  iron-bearing  quartziferous  porphyries  of 
southeastern  Missouri,  a  comparison  previously  made  more 
at  length  by  the  writer  in  a  review  of  the  Rej^oit  for  1873 
on  the  geological  survey  of  that  State.  (Am.  Naturalist, 
April,  1875.)  The  isolated  hills  which  there  rise  through 
the  horizontal  Cambrian  strata  deposited  around  their  base, 
are  in  some  cases  of  quartziferous  porphyry,  and  in  others 
of  a  granitoid  rock,  sometimes  capped  with  the  porphyry, 
which  is  regarded  by  Prof.  Pumpelly  as  a  younger  and  a 
stratififMl  rock.  Wlule,  for  tho  most  part,  a  petrosilex,  some- 
times spherulitic,  and  often  i^orphyritic,  it  may,  as  was  ob- 
served by  the  writer  at  Shepard  Mountain,  become  gneissoid 
from  a  considerable  admixture  of  crystalline  quartz,  inter- 
laminated  with  a  red  granular  orthoclase.  In  one  locality 
these  rocks  include  layers,  sometimes  several  inches  in  thick 
ness,  of  pink  and  greenish  crystalline  carbonate  of  lime, 
interstratilied  with  a  jaspery  schistose  variety  of  petro- 
silex, which,  in  some  layers,  is  intimately  mingled  with  the 
carbonate  of  lime.  In  the  Pilot  Knob,  beds  of  argillite, 
sometimes  more  or  less  talcose  in  aspect,  are  found  with  the 
porphyritic  petrosilex. 

§  374.  Epidote,  chlorite,  and  a  steatitic  mineral  are  occa- 
sionally met  with  in  these  petrosilex  rocks,  and  magnetic 
and  specular  oxyds  of  iron  occur  disseminated,  in  interstrati- 
lied masses,  and  in  veins  intersecting  the  strata,  as  has  been 
well  described  by  Dr.  Schmidt  in  the  report  already 
named.  Oxyds  of  iron,  ;n  some  instances  manganesian,  are 
also  found  forming  the  buGo  of  a  porphyritic  mass,  which 
holds  crystals  of  orthoclase  and  grains  of  quartz,  suggest- 
ing to  Prof.  Pumpelly  the  hypothesis  of  a  replacement 
of  the  petrosilex  itself  by  these  metallic  oxyds.  He  how- 
ever inclines  to  another  hypothesis,  suggested  by  the  ad- 
mixture of  carbonate  of  lime  with  petrosilex,  above  de- 
scribed, and  conceives  that  both  ihepetroeilc:;;  and  the  iron- 
ore  may  have  been  derived  by  a  metasomatic  process  from 
a  limestone,  parts  of  which  were  replaced  by  the  oxyds  of 


iU' 


IIURONIAN   BOOKS   I]^f   NPIWFOUNDLAND.  E.  195 


rgest- 
Iment 
liow- 
[e  ad- 
de- 
liron- 
ll'rom 
[(Is  of 


iron  and  manganese,  "while  the  porphyry  now  surround- 
ing tlie  ores,  may  be  due  to  a  previous,  contemporaneous,  or 
subsequent  repla(;eraent  of  the  lime-carbonate  by  silica  and 
silicates."  The  fact  is  noted  that  chemical  analysis  shows 
that  the  remaining  porphyry,  intimately  associated  with 
the  ore,  or  with  the  limestone,  has  undergone  no  change,  but 
retains  its  normal  constitution,  corresponding  essentially 
to  an  admixture  of  orthoclase  with  quartz. 

§  375.  The  northeastward  extension  of  the  Green  Mount- 
ain range  in  Canada,  its  disappearance,  and  its  re-appear- 
ance in  the  Shickshock  Mountains,  have  already  been  de- 
scribed (§  IGG,  167).  It  remains  to  be  mentioned  that  near 
the  eastern  extremity  of  Gasp<5,  the  rocks  of  this  series, 
consisting  of  chloritic  and  nacreous  schists  with  serpentine, 
appear  in  a  hill  about  thirteen  hundred  feet  in  height, 
which  has  been  named  Mount  Serpentine.  It  is  situated 
on  a  tributary  of  the  river  Dartmouth,  not  far  from  the 
head  of  Gaspd  Bay,  and  rises  in  the  midst  of  the  uncrys- 
talline  sediments  of  the  Quebec  group,  where  its  appear- 
ance is  probably  due  to  a  dislocation.  (Geol.  of  Canada, 
pages  270,  406.) 

^  376.  In  Newfoundland,  the  crystalline  strata  of  the 
Green  Mountain  series  are  largely  developed  both  in  the 
central  and  northwest  parts  of  the  island.  Those  in  the 
latter  region,  were  studied  many  years  since,  and  were  de- 
scribed in  the  Geology  of  Canada  as  belonging  to  the 
altered  Quebec  group.  The  facts  observed  with  regard  to 
their  geological  relations  at  Pistolet  Bay  and  Bonne  Bay, 
have  already  been  given.     (§  218,  219,  226-229.) 

In  1864,  ]\Ii'.  Alex.  Murray  began  a  systematic  geological 
survey  of  Newfoundland,  and  in  hU  first  rej)ort,  in  1805, 
described  with  detail  the  furthiM*  distribution  of  these  crys- 
talline rocks,  which  he  continued  to  regard  as  the  altered 
equivalents  of  the  middle  portions  of  the  Quebec  group, 
occupying  a  jDosition  immediately  below  the  Sillery  sand- 
stone.    (§  352). 

§  377.  The  subsequent  researches  of  Mr.  Murray,  and 
of  his  assistant,  Mr.  James  B.  llowloy,  have  however  led 
them  to  adopt  a  very  different  view,  which  is  set  forth  in 


?n 


It 

^        1: 

.i 

! 

1 

^H' 

; 

'   ^M 

M 

i 

i  It '^H' 

; 

'fll 

' 

196  E.     spp:cial  report,     t.  STicnitY  hunt,  1875. 

the  report  of  tlie  latter,  dated  March,  ISTo,  approved  by 
Mr.  Murray,  and  published  as  a  supplement  to  his  own  i-e- 
port,  in  the  same  year.  The  conclusions  from  Mr.  Ilowley's 
examinations  on  the  east  shore  of  Port-a-Port  Bay,  about 
sixty  miles  southwest  of  Bonne  Bay,  are  that  the  lower 
paleozoic  formations  of  the  region,  supposed  to  include 
Potsdam,  Calciferous,  Levis  and  Sillery,  are  arranged  in  a 
series  of  sharp  folds,  ranging  N.  22°  E.  ;  *'the  whole  mass 
of  strata  having,  towards  the  close  of  the  later  deposits,  or 
subsequently,  been  affected  by  vast  igneous  intrusions,  and 
become  much  dislocated  by  a  set  of  great  parallel  or  nearly 
parallel  faidts,  the  general  trend  of  which  is  northeast  and 
southwest.  At  the  summit  of  the  whole  series  is  a  great 
volume  of  igneous  and  magnesian  rock,  consisting  of  various 
diorites,  serpentines  and  chlorites,  which  our  evidences 
seem  to  indicate  to  be  lapped  over  the  inferior  strata  uncon- 
formably,  and  to  come  in  contact  with  different  members  at 
different  places." 

§  378.  In  the  succeeding  pages  of  the  report,  as  in  tlie 
geological  map  of  Newfoundland,  published  in  1876,  tliis 
whole  magnesian  series  is  designated  as  "serpentines,"  or 
"ophiolites,"  and  we  read,  "further  to  the  northward,  the 
sandstone  group  was  invariably  seen  to  pass  below  the  ser- 
pentines, whi<^h  were  wrapped  over  the  former  in  a  confused 
and  irregular  mass,  the  points  of  contact  differing  at  diifer- 
ent  jjoints  in  such  a  manner  as  (^ould  only  be  accounted  for 
by  supposing  the  ophiolites  to  be  unconformably  related." 
(Report  on  the  Geol.  of  Newfoundland,  187o,  pages  52,  54). 

§  370.  In  a  note  affixed  to  Mr.  Milne's  paper  on  the  geology 
of  Newfoundland,  inthedeological  Magazine  for  June,  1877, 
(page  256),  Mr.  Murray  quotes  the  language  of  the  first  of 
the  above  extracts,  as  expressing  his  latest  opinions  on  the 
relations  of  the  rocks  in  question.  He  says,  moreover,  of  the 
Sillery  sandstone,  "while  we  find  it  to  succeed  the  Levis 
forniati(m  with  perfect  regularity,  although  with  numerous 
folds  and  twists,  in  every  case  it  seems  to  pass  below  the 
serpentines,  wherever  a  contact  is  seen,  and  in  every  case 
to  pass  below  them  unconf ormabl  y. ' '  He  further  concludes 
from  the  presence,  in  the  vicinity  of  Poit-a-Port  Bay,  of 


MURRAY  ON  THE  GEOLOGY  OF  XEWFOUXDLAXD.    E.  197 


comparatively  undisturbed  beds  holding  a  fauna  of  Trenton, 
and  perhaps  of  Loraine  age,  that  "the  great  igneous  in- 


U'vis 
ln'ou8 
IV  the 

case 
hides 
Iv,  of 


trusion  *  *  *  must  be  nearly  at  the  age  of  the  Chazy, 
or  perhaps  later :  that  it  has  been  the  metamorphosing  agent ; 
and  that  the  altered  strata,  consisting  of  chloritic  slates, 
serpentines,  melaphyres,  diorites,  etc.,  belong  to  a  horizon 
somewhere  intermediate  between  the  Chazy  and  Hudson 
River  [Loraine]  group." 

§  380.  The  observations  made  at  Bonne  Bay,  (§  218),  where, 
on  the  northwest  side  of  a  hill  of  these  serpentinic  strata,  the 
Sillery  sandstone,  overlying  conformably  the  fossiliferous 
rocks  of  the  Quebec  group,  is  seen  to  dip  southeastwardly, 
as  if  to  pass  beneath  the  crystalline  series,  is  cited  by  Mr. 
Howley  in  favor  of  the  above  view.  'No  reference  is  how- 
ever made  to  the  different  condition  of  things  described  at 
Pistolet  Bay,  (§219,  227,)  where,  on  the  contrary,  or  south- 
eastern side  of  a  similar  area  of  crystalline  rocks,  the  Sillery 
sandstones  are  said  to  be  found,  occupying  a  breadth  of 
some  miles.  Their  attitude  in  this  localltv  is  not  recorded, 
but  a  little  further  south,  along  the  eastern  coast,  the  same 
sandstones  appea.  in  the  island  of  St.  Julien,  succeeding 
the  serpentinic  series,  though  without  visible  contact,  and 
dipping  away  from  it  to  the  southeast. 

§  381.  The  facts  already  set  forth  show  that  neither 
the  view  of  Logan,  nor  the  later  one  put  forth  by  Murray 
and  his  assistant,  is  admissible,  but  that  the  crystalline 
rocks,  formerly  described  as  belonging  to  the  "altered 
Quebec  group,  "  like  the  similar  rocks  of  the  coast  of  New 
Brunswick,  and  Massachusetts,  belong  to  a  series  older  than 
the  uncrystalline  strata  known  as  the  Quebec  group.  Upon 
this  ancient  crystalline  series,  there  was  deposited  uncon- 
formably  the  Sillery  sandstone,  succeeded  by  the  Lauzon 
and  Levis  divisicms.  In  the  interval  between  this  last  and 
the  Trenton  age,  came  a  time  of  distuibance,  producing 
great  northeast  and  southwest  folds  and  dislocation^,  with 
overturns  to  the  northwest,  and  upthrows  on  the  southeast 
side.  As  a  result  of  these  movements,  the  Cambrian  strata 
on  the  northwest  side  of  the  belt  of  older  crystalline  rocks 
are  very  generally  found  to  be  inverted,  and.  in  parts,  are 


■n 


m 


ii 


fit 


■:  Is 
I 


i  I 


■■  ''1 


I 


I 


198  E.      SPECIAL  REPORT.      T.    STERRY   HUNT,  187o. 

over-ridden  by  the  pre-Cnmbrian  strata,  beneath  which 
they  now  appear  to  pass  unconformably,  as  in  the  sections 
at  Port-a-Port,  Bonne,  and  Pistolet  Bays,  already  de- 
scribed, where  tlie  existence  of  snch  dislocations,  with  up- 
throws in  the  southeast  side,  has  been  pointed  out  (§  219). 

The  structure  above  described  is  well  known  to  be  almost 
universal  along  the  whole  northwestern  bordei-  of  the  At- 
lantic mountain  belt,  from  Canada  to  Alabama,  and  has 
been  described  at  length  by  various  observers  (§  15,  IG,  71- 
81,  177—179). 

§  382.  It  may  be  added  that  the  investigations  of  the 
geological  survey  of  Canada,  during  the  years  1870  and 
1877,  have,  according  to  the  director  of  the  survey,  demon- 
strated the  correctness  of  the  view,  so  long  maintained  l>y' 
the  writer,  that  the  crystalline  rocivs  of  the  Green  Mount- 
ain series  belong  to  a  more  ancient  system,  Avliich  underlies 
unconformably  the  uncrystalline  Cambrian  sediments  of 
the  Quebec  group. 

The  unpublished  observati(ms  of  Prof.  AVilliam  B.  Rogers 
upon  the  similar  strata  in  Virginia  are  to  the  same  effect, 
and  the  writer  is  permitted,  in  this  connection,  to  print  the 
following  extract  from  a  letter  addressed  to  him  by  this 
eminent  geologist,  and  dated  Boston,  June  8,  1877  : 

§  3S3.  "The  sections  which  I  had  the  pleasure  of  showing 
you  lately,  illustrating  the  position  of  the  Lower  Cambrian 
beds  (our  Primal  conglomerate,  etc.)  in  their  contact  with 
the  crystalline  and  metamorphic  rocks  of  the  Blue  Ridge 
in  Virginia,  form  part  of  a  series  embracing  the  results  of 
some  forty  transverse  explorations,  made  during  and  since 
the  Virginia  geological  survey,  at  nearly  er[ual  distances 
a^'ross  the  chain,  from  Harper"  s  Ferry  to  the  North  Carolina 
line.  In  many  of  these  sections  the  unconformity  of  the 
Cambrian  upon  and  against  the  crystalline  and  metamorxiliic 
rocks  is  unmistakable  and  conspicuous  ;  the  lower  mem- 
bers of  the  Primal  being  seen  to  rest  on  the  slope  of  the 
Ridge,  with  northwest  undulating  dips,  <m  the  edges  of  the 
steeply  southeastward-dipiiing  older  rocks.  In  other  cases, 
the  Primal  beds,  thrown  into  southeast  dips  in  the  hills 
which  flank  the  Blue  Ridge,  are  made  to  underlie,  with 


'■  ' 


TIIK  BLUE  RIDGE  IN  VIRGINIA. 


E.  199 


more  or  less  ai^proxiniation  to  conformity,  the  older  rocks 
forming  th(>  central  mass  of  the  mountain.  But  even  in 
these  instances  it  is,  I  think,  not  difficuU  to  discern  the  true 
relations  of  the  strata.  As  interest! iiu-  examples  of  the 
phenomena  referred  to,  I  would  mention  the  sections  ex- 
posed at  Vestal's,  Gregory's.  Snecker's,  and  Manasses  Gaps, 
and  Jeremie's  Run,  in  the  northern  part  of  the  Blue  Ridge  ; 
and  at  Dry  Run,  Turk's,  Tye  River,  White's,  James  River, 
Point  Lookout,  Fox  Creek,  and  Whitetoi)  ^fountain  Gaps, 
in  the  middle  and  southwestern  piolongation  of  the  <liain." 
§  384.  The  crystalline  rocks  which  are  the  prolongation 
of  the  Blue  Ridge  into  southern  Pennsylvania,  have  already 
been  described  as  Iluronian  (§  :]71).  Prof.  W.  M.  Fontaine, 
who,  in  his  late  excellent  jmpers  on  the  geology  of  the  Blue 
Ridge  in  Virginia,  has  c(mlirmed  the  conclusions  of  W.  B. 
Rogers  as  to  the  unconformable  superposition,  and  frequent 
inversions  of  the  lowcn-  paleozoic  rocks  along  its  western 
base,  describes  the  Blue  Ridgo  as  having  an  axis  of  granitoid 
gneiss,  referred  by  him  to  the  Luurentian,  which  is  seen 
near  Lynchburg,  and  in  the  Peaks  of  Otter,  and  further 
south  west  ward.  Resting  unconformably  on  both  sides  of 
this  ancient  series  is  ii  group  of  crystalline  schists,  which, 
to  the  northward,  conceal  the  Laurentian,  and  are  by  him 
compared  to  the  Iluronian.  To  the  eastward  of  the  Lauren- 
tian, and  apparently  occupying  a  synclinal  in  the  schists 
just  mentioned,  is  a  folded  series  of  limestones,  with  quart- 
zites,  micaceous  schists  and  rooliug-slates,  like  the  Lower 
Taconic  rocks  of  Berkshire  county.  Massachusetts,  and  ap 
parently  the  prolongation  of  the  Taconic  belt  noticed  by 
Emmons  to  the  east  of  the  I^lue  Ridge  in  North  C;irolina, 
which  he  declared  to  extend  northward  through  Virginia. 
Beyond  this,  designated  the  middle  Ix^lt,  Fontaine  describes 
an  eastern  belt  of  granitoid  gneiss  overlaid  by  a  series  of 
mica-schists,  with  gneisses  often  hornblendic,  and  said  to 
have  the  characteristics  of  the  White  Mountain  series. 
These  are  displayed  in  broad  undulations,  Avith  moderate 
east  and  west  dix)s,  and  are  less  disturbed  than  the  Iluronian 
rocks  which  lie  further  to  the  west.     (Amer.  Jour.  Science 


200  E. 


SPECIAL    UKPOKT.      T.    STERRY    HUNT. 


I 


. 


Ill,  ix,  14,  0;i,  UOl,  410,  and  Harper's  Annual  Record  for 
1875,  pages  c. — cii). 

§  385.  We  have  seen  that  in  1866  the  South  Mountain 
and  the  Welsh  Mountain  of  Pennsylvania, — the  Northern 
and  Middle  gneissic  districts  of  H.  D.  Rogers — were  already 
regarded  as  Laurentian  (§  44),  In  1876,  the  wi-iter  pre- 
sented to  the  American  Association  for  the  Advancement 
of  Science  the  results  of  some  observations  made  during 
the  previous  year,  in  the  Southern  gneissic  district,  as  seen 
on  the  Schuylkill  to  the  northwest  of  Philadelphia.  The 
rocks  hitherto  described  as  the  northern  division  of  this 
gneissic  district  (§  23)  were  now  declared  to  belong  to  a 
third  Laurentian  belt,  lying  further  to  the  southeast,  but 
nearly  parallel  with  the  preceding  ones. 

§  386.  It  was  said:  "This  La  irentian  belt,  which  is  not 
more  than  a  mile  wide  on  the  river,  [near  Conshohocken, 
on  the  Schuylkill,]  separates  the  Auroral  limestones  of  the 
northwest  from  the  Philadelphia  gneisses  and  mica-schists, 
which  are  typical  rocks  of  the  Montalban  series.  The 
Laurentian  gneiss,  much  contorted,  and  in  parts  nearly 
vertical,  is  succeeded  on  the  southeast  side,  after  a  little 
interval  in  which  the  rocks  are  concealed,  by  a  belt  having 
all  the  characters  of  the  Huronian  series,  in  which  are  in- 
cluded the  large  steatite  quarries  on  both  sides  of  the 
Schuylkill.  These  are  associated  with  dark-colored  ser- 
pentines, chloritic  schists,  unctuous  mica-schists  holding 
garnets,  feldspathic  and  hornblendic  rocks,  and  argillites  ; 
the  section  presenting  most  of  the  typical  rocks  of  the 
Huronian,  in  very  highly  inclined  strata,  which  from  the 
data  given  by  Rogers,  seem  to  have  a  strike  somewhat 
different  from  that  of  the  Laurentian  gneisses." 

§  387.  "This  section  along  the  Schuylkill  has  the  advan- 
tage of  offering,  within  a  short  distance,  and  in  a  very  acces- 
sible place,  charactei'istic  exposures  of  three  great  series  of 
crystalline  formations.  The  intermediate  i)Osition  of  tlie 
Huronian  in  this  section  seems  to  show  that  its  stratigraphi- 
cal  place  is  below  the  Montalban,  and  it  is  to  be  noted  that 
the  dii.)s — generally  moderate — of  the  great  breadth  of 
Montalban  strata,  on  the  one  side,  and  of  the  Auroral  lime- 


PUIMAL  AND  AUllOKAL  IN  PENNSYLVANIA.        E,  201 


'ing 

in- 

the 

ser- 

ling 

tes ; 

the 

the 

^hat 

an- 
3ces- 
?s  of 

the 
plii- 
that 
of 


stone  on  the  other,  are  towards  what  we  nuiy  call  the 
Laurentian  axis.  *  *  *  It  would  seem  as  if  the  Lauren- 
tian  uneiss  had  formed  a  barrier,  h\  the  resisrance  of  whicli 
the  iinconformably  overlying  formations  ImA'e  been  thrown 
into  folds,  and  in  many  cases  faulted,  so  that  they  are  made 
made  to  dip,  on  either  side,  towards  the  axis." 

§388.  "The  Primal  slates  and  sandstones  of  Rogers, 
which  underlie  the  Anroral  niagnesian  limestone,  i)resent 
many  points  of  great  interest.  In  some  places,  as  at  Chicpies 
on  the  Susquehanna,  and  below  Reading  on  the  Schuylkill, 
(where  they  are  seen  to  rest  on  the  Laurentian)  they  are 
api)arently  several  thousand  feet  in  thickness,  while  else- 
where along  the  South  Mountain,  their  only  representative 
is  a  few  feet  of  detrital  sandstone,  interposed  between  the 
Auroral  limestone  and  the  gneiss.''  "The  crystalline  charac- 
ter often  exhibited  by  these  so-called  Primal  strata,  was 
noticed  by  Rogers,  who  asciibed  it  to  their  subsecpient 
alteration  by  intrusive  rocks.  A  careful  study  of  this  series 
has  however  convinced  me  that  its  detrital  beds  include,  in 
many  parts,  deposits  of  chemical  origin,  such  as  beds  of 
crystalline  magnesian  limestone,  often  holding  serpentine, 
chloritic,  steatitic,  and  micaceous  schists,  and  especially 
great  beds  of  magnetic,  and  more  rarely  specular  or  red 
hematite  iron  ores.  *  *  *  The  aspect  of  these  ores,  and 
their  associated  rocks,  is  unlike  that  of  the  other  crystalline 
series  already  mentioned. "  "  These  strata  include  deposits 
of  carbonate  of  iron,  and  others  of  pyrites,  from  the  alter- 
ation of  one  and  the  other  of  which,  in  the  deeply  decayed 
portions  of  these  strata,  (now  converted  into  clays)  have 
been  formed  the  great  quantities  of  hydrous  iron  ores  which 
characterize,  throughout  the  whole  extent  of  their  outcrops, 
the  Primal  and  iVuroral  strata.  These  are  the  Lower  Taco- 
nic  rocks  of  Emmons." 

§  889.  The  intercalation  of  ciystalline  limestones  with 
the  detrital  beds  and  the  crystalline  schists  of  the  Primal, 
was  noticed  by  H.  D.  Rogers,  who  speaks  of  "the  lime- 
stones at  the  passage  of  the  Primal  into  the  Auroral,''  and 
elsewhere  of  "  the  alternations  of  Primal  slate  and  Auroral 


ime- 


m 


I 


202  E.      SPECIAL   REPORT.      T.    STEHRY    H(  NT,    ISTo. 

limestone"  (§35).     These  two  divisions  must  in  fact,  be 
regarded  as  mali^ing  but  a  sin,L!;le  geognostical  series. 

'I'lie  history  both  of  the  crystalline  iron-ores  and  the 
brown  hematites  of  the  Primal  and  Auroral  rocks  had,  pre- 
vious to  the  above  publication,  biurn  discussed  more  at 
length  by  the  writer.  These  rocks,  although  distinct  alike 
from  the  Montalban,  lluionian,  Norian  and  Laurentian 
series,  present  certain  mineralogical  and  lithological  resem- 
blances with  each  of  these.  The  unctU(Mis  schists  of  the 
Primal  and  Auroral,  called  by  Emmons  talcose  and  mag- 
nesian,  have  much  likeness  to  certain  schists  in  the  Iluron- 
ian.  Hence  it  was,  that  after  examining,  for  the  lirst  time, 
in  1874,  the  highly  inclined,  soft  and  decaying  micaceous 
schists  enclosing  the  limonites  of  Fogelsville,  Pennsylvania, 
which  are  found  in  the  Auroral  limestone, — regarded  by 
Rogers  as  occupying  a  jjosition  between  the  Potsdam  and 
the  Trenton  formations  of  the  New  York  series, — the  writer 
insisted  that  these  crystalline  schists  are  very  unlike  any- 
thing found  elsewhere  at  this  geological  horizon,  and  sug- 
gested that  they  b(3longed  to  an  older  crystalline  series, 
which  might  be  Huronian. 

§  390.  In  support  of  the  view  of  the  Eozoic  age  of  these 
limonite-bearing  strata,  he  recited  the  observations  of  Prof. 
C.  U.  Shepard  who,  in  1837,  declared,  with  regard  to  the 
well-known  deposits  of  limonite  in  Salisbury  and  Shai'on, 
Connecticut,  that  "the  ore  is  disposed  in  vast  beds,  with  a 
stratification  everywhere  obvious,  and  perfectly  conforma- 
ble to  that  of  the  adjoining  mica-slate.  It  is  moreover  free 
frt)m  secondary  aggregations."  In  the  town  of  Kent,  simi- 
lar ores,  in  parallel,  highly  inclined  layers,  were  said  to  be 
included  in  a  deposit  known  as  fuller's  earth,  which,  ac- 
cording to  Shepard,  is  a  decomposed  micaceous  gneiss.  In 
other  localities  in  this  region  the  limonites  appears  as  the 
cement  to  a  breccia  containing  fragments  of  quartz.  The 
source  of  these  ores,  it  was  suggested  by  Shepard,  is  to  be 
found  in  the  decomposition  of  sulphuret  of  iron,  and  other 
ferriferous  minerals,  and  he  adds  "it  is  obvious  that  in  a 
majority  of  instances,  the  change  took  jilace  in  the  original 


Iff 


IRON  ORES  AND  THEIR  ORIGIN. 


E.  203 


\U 


repositories  of  these  minenils."  (Mineralogy  of  Coniie«!ti- 
cut,  ])iiges  17,  20,  140). 

^  :J91.  In  i'lirthor  illnstnition  of  tliis  point  tlie  writer  re- 
ferred to  tlie  liinonite  oi-es  formerlv  mined  iilong  tlie  lilue 
liidge,  in  CairoU  county,  V^irginiii,  jind  Du(.'ktoun,  Ten- 
nessee, whieh  are  clearly  of  epigenic  origin,  and  the  oxy- 
dized  outcrops  of  pyritous  lodes,  which,  at  greater  depths, 
have  since  been  exi)loited  for  copper.  These  locks  he 
had  already  described  Jis  being  of  Montalban  age,  to  which 
were  also  referied  tlu;  similar  gneisses  of  the  Iloosac  ^toun- 
tain,  in  Massachusetts,  in  the  decayed  portions  of  which 
was  found  a  layer  of  limonite  ore.  The  fact  was  theu  re- 
called that  all  of  the  various  crystalline  series  of  the  At- 
lantic belt  contain  pyrites,  often  interbedded  in  great 
masses.  Of  these  crystalline  rocks  it  was  said,  "ihe  llu- 
ronian  schists  occasionally  include  beds  of  carbonate  of 
iron,  and  others  of  magnesite  and  dolomite  abounding  in 
carbonate  of  iron,  sometimes  with  much  carbonate  of  man- 
ganese. Emmons  moreover,  thirty  years  since,  noticed  the 
deposits  of  carbonate  of  iron  in  tlie  limestones  and  talcose 
schists  of  his  Lower  Taconic  rocks,  to  whic^h,  according  to 
him,  the  limonites  of  western  Massachusetts  and  eastern 
New  York  l)elong.  From  the  decomposition  and  oxyda- 
tion  of  these  various  minerals,  whether  sulphurets  or  car- 
bonates, hydrous  peroxyds  will  result,  and  hence  we  should 
exi)ect  to  find  them  wherever  these  decayed  rocks  have 
escaped  erosion."  (Trans.  Amer.  Inst.  Mining  Engineers, 
III,  419,  420). 

§  302.  Subsequent  studies  in  1875,  in  Pennsylvania,  made 
it  clear  that  the  decayed  crystalline  schists  which  there  con- 
tain the  limonites,  were  not  Iluronian  but  Taconic.  Tlic^se 
conclusions  wore  set  forth  in  a  paj^er  on  The  Cornwall  Iron 
Mine,  and  some  rehited  dejwsits,  read  before  the  Institute 
of  Mining  Engineers  in  February  1870,  and  published  in  the 
Transactions  (IV,  319-325). 

It  was  there  said  that  the  crystalline  magnetic  and  specu- 
lar iron  ores,  represented  by  the  mines  of  Cornwall.  Dills- 
burg,  and  Boyertown,  and  the  Warwick  and  Jones  mines, 
found  along  the  borders  of  the  Mesozoic  basin  of  Pennsyl- 


r 


T 


204  E.      SPECIAL   REPORT.      T.   STERRY    IIUXT,    ISTH. 


I 


vania,  are  not  tx)  be  confounded  with  the  ores  of  Huronian 
or  of  Laurentian  age,  but  "alike  by  their  geological  j^osi- 
tion  and  their  mineralogical  associations  differ  from  thf)se, 
*  *  and  appear  to  belong  to  a  distinc't  ore-bearing  hori- 
zon."    "These  ores  were  by  Prof.  H.  D.  Rogers  referred  to 


what  hf»  designates  as  the  Primal  slates, 


*    * 


thouii'li  bv 


some  Ititer  observers,  the  Cornwall  mine,  and  certain  related 
dejiosits  west  of  the  Susquehanna,  have  been  referred  to 
the  Mesozoic  sandstone."  The  conclusion  then  reached 
however,  was  that  "they  are,  all  of  them,  really  contempo- 
raneous deposits  included  in  the  Primal  slates,  Avhich  cor- 
respond to  a  portion  of  the  Lower  Taconic  series  of  Em- 
mons, and  belong,  in  my  opinion,  to  a  lower  horizon  than 
the  Potsdam  sandstone  of  the  New  York  system."  "  These 
magnetic  and  sjjecular  ores  of  the  Primal  slates  have  very 
close  get>logical  relations  with  the  brown  hematites  of  the 
region,  s(mie  of  which  belong  to  the  same  Primal  slates. 
These  ores,  which  I  believe  to  come  fnmi  the  alteration  of 
deposits  of  car1)onate,  and,  in  many  cases,  of  sulpliuret  of 
iron,  oxydized  in  sit'O,,  are,  in  certain  deposits  of  the  re- 
gion, interstratified  with  crystalline  magnetic  and  specular 
oxyds  ;  the  whole  being  imbedded  in  the  clays  which  have 
resulted  from  the  more  or  less  complete  decomposition  of 
the  enclosing  crystalline  rocks." 

§  394.  The  micaceous  substance  which  makes  up  a  con- 
siderable part  of  the  residue  remaining  after  the  decay  of 
these  schists  (which  rre  often  impure  limestones,)  has  been 
found  by  Genth  to  have,  in  many  cases,  the  composition  of 
a  hydrous  non-magnesian  potash-mica,  referred  by  him  to 
the  species  damourite.  This  however  is  not  always  the 
case,  since  both  talc  and  chlorite  are  found  in  the  Primal 
slates  of  the  Cornwall  mine,  and  chlorite,  with  garnet,  in 
those  of  the  Jones  mine.  Tlie  latter  moreover  includes 
beds  of  an  apparently  decayed  rock,  which  has  been  mined 
as  an  ore  of  copper,  and  consists  in  large  part  of  a  soft  pale 
green  mineral,  in  minute  scales,  resembling  in  aspect  the 
hydrous  mica  above  mentioned.  Analysis  however  sliows 
it  to  be  a  li\  drous  silicate  of  alumina,  ferric  and  cupric 
oxyds,  and  magnesia,  constituting  a  kind  of  copper-chlo- 


TALCOSE  ok  NACKEOCS   SLATES. 


E.  205 


the 
imal 
in 
ides 
ined 
nnle 
tlie 
ows 
pric 
hlo- 


rite,  wliicli  has  been  described  by  the  author  as  a  new  spe- 
cies, under  the  name  of  venerite  (Trans.  Amer.  Inst.  Min- 
ing Engineers,  lY,  32G.) 

§  39.5.  The  soft  and  unctuous  schists  of  tlie  Taconic  were 
by  Emmons  designated  magnesian  slates  or  talcose  slates, 
and  the  hitter  name  was  also  given  to  the  somewhat  similar 
schists  found  in  the  Huronian  series,  with  which  the  former 
were  generally  confounded,  although  Emmons  clearly  distin- 
guished between  the  talcose  slates  of  the  Taconic,  and  those 
of  what  he  called  the  Pi'imarv  rocks.  In  18.j5,  the  writer, 
having  examined  many  oL'  the  talcose  slates,  from  both  se- 
i-ies,  announced  that  they  contained  little  or  no  magnesia, 
and  were  essentially  hydrous  silicates  of  alumina,  belong- 
ing to  the  class  of  minerals  represented  by  i)yropliyllite, 
pholerite,  etc.  To  avoid  the  perpetuation  of  an  error,  he 
therefore  prf)i)osed  for  these  unctuous  aluminous  schists, 
in  allusion  to  thek  pearly  lustre,  the  name  of  nacreous 
slates  (Amer.  Jour.  Sci.,  II.  xix,  417). 

§  89G.  Emmons  soon  after  described,  in  IS^G,  the  occur- 
rence of  a  soft  compact  mineral,  locally  known  as  soap- 
stone,  which,  according  to  him,  occurs  in  many  i)arts  of 
North  Carolina,  interstratiJied  witli  the  quartzites,  talcose 
slates  and  limestones  of  the  Lower  Taconic  series,  in  wliicli 
it  "takes  the  place  of  steatite."  This  substance,  which  is 
white,  or  greenisii-w^hite  in  color,  and  sometimes  holds  crys- 
tals of  magnetite,  having  been  analyzed  by  Dr.  C.  T.  Jack- 
s(m,  was  I'cmnd  to  be  essentially  a  hydrous  silicate  of 
alumina,  and  by  him  referred  to  agalnuitolite,  a  name  which 
was  adopted  by  Emmons.  (Geol.  Midland  Counties,  N. 
Car.,  pages  52-oo,  127,  and  Proc.  Bost.  Soc.  Nat.  Ilist.,  VI, 
33).  Brush,  in  1858,  showed  that  wliat  had  hitherto  been 
called  agalmatolite,  was  really  l)ut  a  compact  pyrophyllite, 
which  he  correctly  described  as  an  aluminous  talc.  (^xVmer. 
Jour.  Sci.  II.  xxvi.  08). 

§  397.  It  thus  ai)pears  that  besides  the  foliated  magiiesian 
minerals,  talc,  chlorite  and  venerite,  all  of  which  are  occasion- 
ally met  with  in  the  Taconic  schists,  these  are  various 
micaceous  hydro-silicates  of  alumina,  including  pyroj)hy]  lite 
and  damourite,  which  eithei-  jMire.  or  mingled  wiili  i|iiait/.. 


M 


I  : 


2(J6  E.     special  report,     t.  sterry  hunt,  1875. 


I 


enter  into  the  composition  of  the  so-called  talcose-schists, 
originally  designated  nacreous  slates  by  the  writer,  and  now 
frequently  spoken  of  as  hydro-nuca  slates. 

§  398.  As  regards  the  relation  of  the  Lower  Taconic  series 
to  organic  life,  it  is  well  known  that  the  Primal  white  sand- 
stone, in  various  localities  from  Massachusetts  to  Tennessee, 
contains  a  form  described  as  Scolithus,  of  which  the  history 
has  been  given  at  length,  (§  200).  In  a  communication  by 
the  writer,  in  the  Proceedings  of  the  American  Association 
for  the  Advancement  of  Science  for  1870,  (page  208),  it  was 
stated  that  Prof.  Prime  had  lately  found  in  the  Auroral 
limestone  of  Pennsylvania,  besides  an  undescribed  Lingula, 
certain  casts  which  Dr.  Torell,  after  examination,  regarded 
as  generically  identical  with  those  found  in  the  Eophy ton- 
sandstone  of  Sweden,  and  supposed  to  belong  to  a  radiate 
animal,  to  which  he  had  given  the  name  of  Monocraterion^ 
(§  250).  It  is  not  improbable  that  these  casts  in  the  lime- 
stone in  Pennsylvania  may  be  due  to  the  same  organism 
which  has  produced  the  Scolithus  of  the  Primal  sandstone. 
The  relations  of  this  Primal  and  Auroral  series,  both  to  the 
Eophyton-sandstone  of  Norway,  and  to  the  series  of  lime- 
stones, talcose-slates  and  quartzites  which  are  fountl  in 
southern  Norway,  at  the  base  of  the  Cambrian  series,  and 
are  by  Kjerulf  named  Lower  Taconic,  (§  257),  are  subjects 
for  further  inquiry. 

Under  the  name  of  PalccotrocJi  is,  Emmons,  in  1850,  de- 
scribed what  he  conceived  to  be  a  silicious  coral,  found  in  the 
quartzites  of  the  Lower  Taconic  in  Troy,  Mt)iitgomery 
county.  North  Carolina,  but  there  does  not  seem  to  be  any 
good  ground  for  regarding  it  as  of  organic  origin,  (Geol. 
of  the  Midland  Counties  of  N.  Car.,  page  00;  and  Chem. 
and  Geol.  Essays,  page  411), 

§  399.  We  have  given  reasons  for  regarding  the  Lower 
Taconic,  or  the  Primal  and  Auroral  strata  of  the  great  Ap- 
palachian valley,  as  the  equivalents  of  the  similar  series  in 
southern  New  l^runswick,  (^  344),  and  of  the  Hastings  series 
in  Ontario,  (§  331,  341),  with  its  Scolithus  and  Eozoon.  While 
it  has  been  shown,  in  a  preceeding  chapter,  that  the  Upper 
Taconic  includes  the  organic  remains  of  the  European  Cam- 


BLUE   KIDGE  IN   NORTH   CAROLINA. 


E.  207 


brian,  at  least  as  low  as  the  Menevian,  it  is  by  no  means 
certain  whether  the  Lower  Taconic  series  is  to  be  regarded 
as  the  equivalent  of  the  still  lower  beds  of  the  Cambrian  of 
Great  Britain  and  Sweden.  In  this  uncertainty  it  is  deemed 
well  to  preserve  for  this  series  the  original  name  of  Taconic, 
or  better,  Taconian.    (Proc.  Bost.  Soc.  Nat.  Hist.,  XIX.  278). 

§  400.  Some  recent  observations  by  the  writer  on  the 
crystalline  rocks  of  the  Blue  Ridge,  are  given  in  a  commu- 
nication to  the  Boston  Society  of  Natural  History.  (Pro- 
ceedings, etc.,  XIX,  277.)  Attev  noticing  the  presence  of 
rocks  both  of  Montalban  and  Iluroniau  ages,  on  the  line  of 
the  Baltimore  and  Ohio  railroad,  (the  latter  near  Harper's 
Ferry,)  and  the  existence  of  Laurentian  gneisses  at  Bell- 
isle,  near  Richmond,  Virginia,  some  account  is  giv'en  of  the 
crystalline  rocks  seen  in  a  section  across  the  Blue  Ridge, 
in  Mitchell  county.  North  Carolina. 

"The  gneisses  of  Roan  Mountain,  and  similar  rocks  at 
its  western  base,  which  inchule  the  great  masses  of  mag- 
netite, are  Laurentian,  but  indications  of  a  belt  of  Iluronian 
schists,  associated  with  specular  iron-ore,  are  found  on  the 
western  flank  of  the  mountain.  To  the  eastward,  the  Lau- 
rentian rocks  are  succeeded  by  a  great  breadth  of  thin- 
bedded  gneisses,  with  highly  micaceous  and  hornblendic 
schists,  referred  to  the  Montalban  series,  in  which  is  included 
the  narrow  belt  of  dunite,  or  olivine  rock,  found  near  Ba- 
kersville.  Tliesc  Montalban  stnita  are  intersected  by  nu- 
merous endogenous  granitic  veins,  wldcli  are  largely  ex- 
jiloited  for  mica,  and  yield,  moreover,  line  cleaval)le  masses 
of  orthoclase,  and  of  albite,  together  with  beryl,  apatite, 
samarskite,  and  autunite.  The  rocks  of  this  series,  often 
deeply  decomposed,  were  found  to  occupy  the  greater  part 
of  the  ';ountry,  as  far  east  as  Salisbury,  interrupted,  how- 
ever, near  Statesville,  on  the  Western  North  Carolina  rail- 
road, by  gi'anitoid  gneisses,  which  have  th(3  characters  of 
Laurentian."  (For  some  notice,  by  the  writer,  of  the  metal- 
liferous veins  in  the  Montalban  rocks  of  the  Blue  Ridge 
in  Virginia,  North  Carolina  and  Tennessee,  see  Transactions 
Amer.  Inst.  Mining  Engineers,  II,  123,  and  Chem.  and  rfcoj. 
Essays,  page  217.) 


w 


208   E,       SPECIAL    UKPOIiT.       T.    STEUPvV  HUNT,  187o. 

§  401.  "The  belt  consisting  of  granular  quartz-rock,  with 
limestones  and  hydrous  mica-slates,  which  was  seen  at 
the  eastern  base  of  the  Blue  Ridge,  on  the  Catawba  river 
near  Marion,  North  Carolina,  has  all  the  characters  of  the 
Lower  Taconic,  to  which  it  was  long  since  referred  by  Em- 
mons. Portions  of  this  quartzite  are  thinly  bedded  and 
flexible,  constituting  what  is  known  as  itacolumite.  It  is 
regarded  by  the  writer  as  identical  with  the  Primal  white 
sandstone  of  Pennsylvania,  whi(;h,  with  the  Auroral  lime- 
stone, and  its  interstratiiied  and  overlying  unctuous  schists, 
and  the  succeeding  rooling-slates,  constitute  a  distinct  geo- 
logical horizcm." 

§  402.  In  his  rept)rt  on  the  Geology  of  North  Carolina,  in 
IBTf),  and  in  the  colored  geological  map  and  sections  ac- 
companying it,  Prof.  Kerr  has  included  the  whole  of  the 
crystalline  stratified  rocks  of  the  State  under  two  heads, 
Laurentian  and  Ilurouian.  The  former  of  these,  both  in 
the  text,  and  in  the  legend  of  the  ma]),  he  divides  into 
Lower  and  Ui)per  Laurentian,  though  in  the  ac('omi)anying 
colored  sections,  the  Lower  division  is  called  "granite." 
The  name  of  Upper  Laurentian,  originally  given  by  the 
geological  survey  of  Canada  to  an  entirely  different  group 
of  rocks,  the  Noiian  or  Labradorian,  is  by  Prof.  Kerr 
ai)plied  to  the  series  of  gneisses  and  micaceous  and  horn- 
blendic  schists,  (with  included  beds  of  chrysolite-rock,) 
which  is  that  described  by  the  writer  in  the  above  section, 
as  the  Montalban,  of  which  it  has  all  the  characters  ;  Avhile 
the  rocks  of  the  Roan  Mountain,  called  by  Prof.  Kerr, 
Lower  Laurentian,  are,  as  already  stated,  true  Laurentian. 

^  403.  Under  the  head  of  Iliii'onian,  Prof.  Kerr  informs 
us  he  has  included  the  Taconic  series  of  Emmons,  including 
the  (jiiartzites  witli  the  so-called  Falcmtroclih,  the  itacol- 
imiite  or  iiexible  sandstone,  the  hydrous  mica-schists,  the 
argillit(^s,  often  ])lumbaginous,  and  the  pyrophyllite  beds, 
togvt  her  with  the  granular  limestones  and  marbles,  often  ac- 
<'oMi[)aiiied  by  limonites.  The  qiuutzites  of  this  series, 
like  those  of  the  same  liorizon  in  Pennsylvania,  often 
abound  in  magnetic  and  specular  iron-ores,  and  sometimes 
jiass  into  a  speculai-  schist  or  itabirite.     This  series  is  de- 


PUK-CAMBKIAN    AGE   OF   TIIK    I5LUE    KIIM'.E.       E.    'iOi) 


scribed  by  Prof.  Kerr  ;is  resting  upon  the  Uppei*  Lauren- 
tian,  (Monta'ban)  and  in  part  made  up  of  its  ruins,  lie 
has  indicated  not  less  than  live  parallel  belts  of  tJiese  so- 
called  lluronian  rocks,  stretching  from  northeast  to  south- 
west, in  Xorth  Carolina,  one  of  which  includes  nieTaconiiin 
rocks  noticed  by  the  writer  :it  the  eiistern  base  of  the  Blue 
Uidgc,  in  th(^  section  described  above.  It  remains  to  be  de- 
teiinined  Nvhere,  and  to  what  extent,  true  lluronian  i-ocks 
occur  within  the  limits  of  North  Carolina,  but  it  appears 
not  improbable  that  some  of  the  more  massive  portions  of 
the  lluronian  may  be  included  in  the  rocks,  which  under 
the  names  of  greenstones  and  I'eldspai'-porpliyries,  aresaid- 
by  Prof.  Kerr,  to  occur  in  parts  of  the  so-called  Upper  Lau, 
rentian  areas. 

§  404.  AVe  may  in  this  j^lace  notice  the  vi-  s  of  Prof.  F. 
Bradley,  who,  arguing  chieily  from  a  supposed  i)arallelisui 
between  the  various  groups  of  crystalline  rocks  and  the 
dilferent  paleozoic  formations  of  the  Champlain  divisi(m, 
has  recently  been  led  to  put  forth  anew  the  old  hypothesis 
of  the  paleozoic  age  of  the  crystalline  sti-ata  of  the  Atlantic 
belt,  and  to  suggest  that  the  l>liu'  IJidge,  in  North  Carolina 
and  'i'ennessee,  consists  of  altered  Cambrian  and  Siluro- 
CVunbrian  rocks  (Amer.  Jour.  Sci.  Ill,  ix,  '27i),']7()). 

To  this  hypothesis,  a  conclusive  answer  is  furnislied  by 
the  observations  of  W.  B.  Rogers,  and  of  Fontaine,  already 
quoted,  as  to  the  rehitions  of  the  basal  paleozoic  rocks  to 
the  crystalline  schists,  and  by  the  express  declaratiou  of 
tlie  latter  that  certain  of  these,  desci'ibed  by  him  as  aru,il- 
lites,  were  in  their  present  condition  before  the  Pi'imordial 
(either  Taconian  or  Cambiian)  period,  (ibid.  Ill,  ix,  'U)7)  as 
apjx'ars  from  the  fact  that  fragments  of  these  are  found, 
together  with  feldspathic  debris,  in  the  Primordial  con- 
glomerates. From  this,  he  concludes  that  the  crystallim^ 
rocks  of  the  Blue  Ridge  foruied  the  southeastern  boi'der  of 
the  ])aleozoi(;  sea;  while  Bradley,  on  the  coutrary,  imagiues 
these  same  rocks  to  be  themselves  ])aleozoic  strata,  which 
were  uplifted  and  altered  after  the  close  of  the  pahM)Zoic 
period.  The  observations  of  Fontaine  ai'e  couliruied  by 
those  of  the  writer,  who  has  found  in  southwestern  Wv- 

114  K.l 


^ 


210  E.      SPECIAL   REPORT.      T.  STERRY  HUNT,  1875. 


ginia,  pebbles  of  gneiss  and  of  mica-schist,  apparently 
Montalban,  in  tliese  basal  conglomerates  (Harper's  Annual 
Record,  1875,  pages  c — cii). 

§  405.  We  have  already  adverted  to  the  fact  that  the  five 
great  groups  of  crystalline  stratified  rocks,  constituting  as 
many  distinct  terranes  —  Laurentian,  Norian,  Iluroiiian, 
Montidban  and  Taconian,  necessarily  have,  notwithstand- 
ing their  differences,  certain  lithological  resemblances  with 
each  other.  All  of  them  include  quartzites,  and  crystal- 
line limestones,  in  which  latter  certain  mineral  silicates, 
such  as  serpentine,  hornblende,  and  micas  are  occasionally 
met  with.  It  is  in  those  alumiuiferous  rocks  which  are 
without  lime  and  magnesia,  that  are  found  the  essential 
and  characteristic  differences,  and  these  depend  upon  the 
principle,  set  forth  in  detail  by  the  writer,  in  18G3,  of  a  pro- 
gressive diminution  in  the  proportion  of  the  alkalies  to  the 
alumina,  (Chem.  and  Geol.  Essays,  page  27)  as  we  pass 
from  the  older  to  the  newer  geognostical  groups.  In  accord- 
ance with  this,  the  feldspars,  orthoclaseandalbite,  gradually 
disappear,  being  partially  or  wholly  replaced  by  silicates 
like  muscovite,  damourite  and  paragonite,  and  finally 
by  andalusite,  fibrolite,  cyanite,  stauroliteandpyrophyllite. 
These  various  silicates  are  scarcely  known  in  the  Lauren- 
tian and  Norian,  though  they  are  represented  to  a  limited 
extent,  by  certain  quartzose  mica-schists,  in  the  Huronian. 
In  the  Montalban,  they  appear  to  a  considerable  extent,  and 
have  their  most  complete  crystalline  development  in  cer- 
tain beds  in  that  series,  although  oithoclase  still  predomi- 
nates in  the  associated  gneisses. 

§  40G.  In  the  Taconian  rocks,  on  the  contrary,  the  feld- 
spars are  but  rarely  and  excej)tionally  developed,  while  hy- 
drous silicates  of  alumina,  such  as  damourite  and  paragonite, 
or  pyrophylite,  which  is  destitute  of  alkali,  abound,  and 
either  alone  or  mingled  with  quartz,  or  with  limestone,  form 
great  beds  in  the  series,  in  which  also  are  found  stauro-" 
lite,  chiastolite  and  cyanite,  though  generally  not  so  well 
defined  as  in  the  ;Montall>an,  which  is  easily  distinguished 
from  the  Taconian  by  its  great  development  of  strong  mica- 
scliistSj  well-marked   gneisses,   and  blackish    hornblendio 


RELATIONS  OF  TACONIAIN'  TO  PALEOZOIC  TIME.    E.    211 


cer- 
lomi- 

,Md- 
liy- 

and 
Ifoim 
luiro-' 

well 
[shed 
liiica- 

Midio 


schists.  (Chem.  and  Geol.  Essays,  page  244).  It  is  by  a 
misconception  that  some  have  been  led  to  regard  the  pres- 
ence of  staurolite,  cyanite  and  andalusite,  as  exclusively 
characteristic  of  the  Montalban,  a  proposition  nowhere 
maintained  by  the  writer,  since,  although  they  have  not  been 
found  in  the  oldest  terranes,  these  mineral  species  have 
long  been  known  to  occur,  in  many  localities,  in  the  Tacon- 
ian  schists. 

§  407.  The  question  has  arisen  wheth(n'  these  crystalline 
rocks  of  the  Taconian  series,  occupyinr  i\  position  between 
the  Montalban  below,  and  the  recognized  Cambrian  above, 
are  to  be  regarded  as  «jozoic,  or  as  paleozoic.  In  the  lan- 
guage used  by  the  ^vTitei,  in  1876,  in  answer  to  this  question : 
"  It  will  be  found  as  difficult  to  draw  the  line  between  the 
eozoic  and  paleozoic,  as  it  is  to  define  that  between  the  mes- 
ozoic  and  tlie  paleozoic,  on  the  one  hand,  or  the  mesozoic  and 
the  cenozoic  on  the  other.  There  are  no  hard  and  fast  lines 
in  nature  ;  breaks  are  local,  and  there  is  nowhere  an  appa- 
rent hiatus  in  the  geological  succession,  which  is  not  some- 
where filled."  Referring  to  the  Liiigulu  of  the  Auroral 
limestones,  it  was  then  suggested  "that  this  seemingly 
imperishable  type  of  brachiopods  may  serve,  like  the 
rhizox^ods,  represented  by  Eozoon,  as  a  connecting  link  be- 
tween eozoic  and  paleozoic  time."  (Proc.  Assoc.  Advan. 
Science,  187G,  pages  207,  208). 

§  408.  We  have  already  noticed  in  §  119 — 122  some  of  the 
various  and  contradictory  liypotheses  i)at  forth  \\  itli  regard 
to  the  age  of  the  Taconian  or  Stockbridge  limestones,  as  dis- 
played in  western  New  Enghmd.  According  to  II.  D. 
Rogers,  they,  like  the  Auroral  limestone  of  Pennsylvania, 
are  of  the  age  of  the  Calciferous  and  Chazv  of  the  New 
York  series,  while  by  Adams  and  others  they  have  been 
supi'josed  to  be  either  Lower  Ilelderberg  or  Dcnonian.  Ma- 
ther, and  later  Dana,  have  maintained  that  they  are  of 
Trenton  age,  while  Logan,  in  his  geohigical  niaj),  published 
in  ISGG  (§  44)  has  represented  them  as  the  Levis  division  of 
the  Quebec  group,  or  Upper  Taconic — the  original  charac- 
ters of  the  linu^stones,  in  all  cases,  being  supposed  to  have 
been  greatly  modified  by  a  subsequent  process.     Of  these 


r 


i  '    J 


212   E.      8PECIAL   IIKPOKT.      T.  STERRY  IIUXT,  187o. 


four  irreconcilable  views,  each  one  in  its  turn,  has  been 
plausibly  defended  upon  the  ground  of  apjiai'ent  sui)erpo- 
sition  to,  or  of  association  with  fossiliferous  strata  of  dif- 
ferent horizons,  in  one  or  more  localities. 

§  400.  It  has  long  been  known  that  the  more  ancient 
folded  and  faulted  strata,  along  the  Atlantic  belt,  include 
jMU'tions  of  newer  formaticms,  of  various  ages,  and  nioi-e- 
over  that  tiue  natural  order  of  the  strata  is  so  generally  in- 
verted, that  the  newer  formations  pass,  or  seem  to  pass, 
beneath  the  older.  Of  this,  a  marked  example  has  been 
given  in  §  2132,  where,  in  Fandiam,  in  the  x>rovince  of  Que- 
bec, the  strata  holding  a  Hiluro-Caml)i'ian  fauna,  were  as- 
signed a  position  at  the  base  of  the  Quebec  group.  The 
observations  of  Wing,  and  of  Billings,  have  shown  the  ex- 
istence of  siuiilar  examples  in  western  Vermont  (§  20.")) 
which  have  more  recently  been  discussed  bv  J.  D.  Dana. 
The  similar  strata  on  the  eastern  side  of  the  Green  Mount- 
ains, in  northeastern  Vernu)iit  aiul  Canada,  referred  to  by 
Logan  (§  331),  are  accompanied  by  fossiliferous  strata  of 
Lower  llelderbergor  Devonian  age. 

P^urther  southward,  in  the  valley  of  Virginia,  Devonian 
and  Carboniferous  strata  become  involved  in  these  disturb- 
ances, and  are  seen  to  dip  at  high  angles  to  the  southeast- 
ward, apparently  passing  beneath  the  Taconic  or  Auroral 
limestones.  (Comjiare  Emnums,  Amei-.  Geol.,  II,  04,  and 
Lesley,  Proc.  Amer.  Philos.  Soc,  XII,  480). 

§  410.  The  argument  of  those  who  ignore  these  facts  of 
structure,  and  adopt  the  liyi)otliesis  of  metam()ri)hisui,  may 
thus  be  stated:  Fossiliferous  strata  included  in  folds,  or  in 
faults,  are  supposed  to  lix  the  age  of  the  entire  series  in 
question,  while  the  absence  of  organic  remains  from  other 
parts  of  the  section  is  accounted  for  by  the  assumed  meta- 
morphosis of  these  parts.  The  faith  of  some  believers  in 
this  hypothesis  has  frequently  led  them  to  mistake  obscure 
and  doubtful  markings  in  (Tystalline  rocks,  for  vestiges  of 
organic^  life.  A  sti'iking  exauiple  of  this  is  alfonled  by  the 
supposed  brachiopods  and  tiilobites,  upon  which  it  was  at 
one  time  attempted  to  establish  the  Silurian  age  of  the 
White  Mountain  gneisses  and  mica-schist^      (§  123). 


DANA    ON    THE   TACONIC    QIAKTZITES. 


E.  21:3 


in 
lure 

of 
Ithe 

at 
Ithe 


§  411.  The  late  notes  of  Dana  on  tlie  geology  of  Vermont 
contuin  some  observations  on  this  point,  which  are  not  the 
less  instructive  that  they  come  from  an  extreme  advocate 
of  the  iiietamori)liic  hypothesis.  Describing  a  quartz  rock, 
which  in  New  Haven,  Vermont,  is  int(?rstratilied  in  lime- 
stones supposed  to  belong  to  the  Taconic-  series,  he  says: 
"The  (piartzite  is  in  most  parts  a  little  slaty  in  sti'ucture, 
and  in  Hunted  ptntions,  a  shining  grayish-black  slate.  In 
places  over  it  areareas  of  sub-concentric  condioidal  lamina- 
ti(m,  looking  somewhat  as  if  <'x:imples  of  the  tiow-and- 
pluuge  structui'e,  but  more  probably  a  result  of  concreticm- 
ary  consolidation.  To  the  latter  cause,  I  attribute  some 
forms  that  looked  exceedinglv  like  casts  of  a  Phiivolo- 
HKiria  and  a  Murdiisonia,  and  of  a  valve  of  Orthis  hjnx. 
Others  of  these  imitative  forms,  over  the  surface,  were  serai- 
cylindrical  and  chambered,  as  if  worn  casts  of  long  cri- 
noidal  stems,  yet  having  the  chambers  too  large  and  irregu- 
Lir  for  any  known  crinoidal  forms.  These  simulations 
of  crinoids  may  also  be  due  to  a  concentric  structure  in  the 
slaty  portion  of  the  rock,  yet  how,  it  is  not  easy  t(j  unchH'- 
stand."     (Amer.  Jour.  Sci.  Ill,  xiii,  409). 

§  412.  Dana  has,  in  this  connection,  given  a  figure  of 
natural  size,  of  a  portion  of  one  of  these  chambered  cylin- 
ders, which  had  a  total  length  of  twenty-five  centimeters. 
It  is  represented  as  divided  by  transverse  sei)ta  of  about 
one  milliuK^er  in  thickness,  into  ('hambers  having  a  length 
of  three  centimeters,  more  or  less,  and  a  breadth  of  six  cen- 
timeters. The  walls  of  the  cylinder,  in  the  drawing,  are  not 
distinguished  from  the  enclosing  rock.  The  figure  bears 
such  a  close  resemblance  to  the  transversely  waved  or 
grooved  casts  of  so-called  Scolithus  from  the  Primal  sand- 
sttmes  of  Pennsylvania,  (^  206,  208),  which  probably  I)elong 
to  the  same  horizon,  that  it  seems  highly  jirobabhi  that 
these  hollow  casts  mav  be  due  to  the  same  cause,  and  tluit 
they  are  of  organic  origin. 

§  413.  It  is  not  improbable  that  the  Taconian  rocks  may 
include  other  forms  than  Scolithus  and  Monocraterion,  and 
the  undescribed  lingultjid  shell.  In  their  study,  however,  it  is 
necessary  to  l)e\vare,  on  theone  hand,  of  mistakingsuchcon- 


I 


214   E.      SPECIAL    REPORT.      T.  STERRY  IITJIS'T,  1875, 


i 

* 

;  i_ 

■     7? 

■i 

it 

1 

■  7 

cretionary  miirkings  as  tliose  already  mentioned,  for  organic 
remains,  and  on  the  other  to  avoid  the  error  of  referring  to 
these  older  rocks,  what  are  perhaps  portions  of  newer  strata 
resting  npon  them,  or  involved  in  their  folds  or  dislocations. 
The  rocks  thus  brought  together  may  differ  so  widely  in 
Lithological  characters  that  it  is  easv  to  discriminate  be- 
tween  them,  but  in  other  cases  the  task  is  much  more  diffi- 
cult, as  in  the  example  of  some  fossiliferous  Silurian  beds 
in  southern  New  Brunswick,  made  up  almost  wliolly  of 
the  disintegrated  Huronian  greenstones,  in  the  midst  of 
which  they  were  deposited.  Another  example  is  that  of 
the  Trenton  limestones  of  Hastings  county,  Ontario,  which 
resemble  so  closely  some  of  the  bluish-gray  enrthy  beds  of 
the  underlying  Taconian,  that  it  is  very  easy  to  mistake 
the  one  for  the  other  (§  333).  The  difficulty  of  distinguish- 
ing between  these  two  formations  would  be  greatly  en- 
hanced were  the  newer  rocks  involved  with  the  older  in  a  se- 
ries of  folds,  inversions  and  dislocations,  as  in  the  case  in  the 
Appalachian  valley.  When  we  add  to  this,  the  of  jirocess 
decay,  which  has  converted  the  slaty  and  impure  i:)ortions  of 
the  Auroral  limestone,  for  considerable  depths,  into  a  soft 
and  yielding  material,  it  is  evident  that  the  localities  of 
fossiliferous  limestones  in  such  a  region  should  be  scanned 
with  the  gi'eatest  care. 

§  414.  Prof.  Prime,  in  a  late  paper  on  the  limestones  of 
this  valley,  in  Lehigh  and  Northampton  counties,  Pennsyl- 
vania, after  mentioning  the  Monocraterion  and  Lingula,  al- 
ready pointed  out  (§  398,)  each  of  which  has  been  found 
only  at  one  locality  in  Lehigh,  notices  the  occurrence,  in  the 
same  county,  of  a  single  0?i7ioceras,  too  imperfect  to  be  de- 
termined, and  a  specimen  of  Eriomplialus.  Both  of  these 
are  supposed  to  occur  in  the  Auroral,  wliich  however  has 
not  yielded  a  single  organic  fossil  in  Northampton  county. 
Overlying  the  Auroral,  in  these  counties.  Prof.  Prime  finds, 
at  intervals,  portions  of  an  argillaceous  limestone,  containing 
in  abundance  the  characteristic  forms  of  the  Trenton,  such 
as  CJicctetes  lycoperdon^  and  Orthls  pecilnella^  withcrinoi- 
dal  stems.  This  limestone  is  said  to  differ  from  the  Au- 
roral in  being  ' '  more  compact,  and  not  at  all  crystalline,  and 


RELATIONS  OF  THE  VAIIIOUS  EOZOIC  SEIIIES.      E.    215 


of  a  gray-black  color."  It  is  clescri])ed  as  "apparently  con- 
fomiable"  with  the  Auroral,  (Proc.  Amer.  Pliilos.  Soc, 
Dec.  21,  1877). 

§  415,  From  his  own  observations  in  this  region  in  1875, 
the  writer  was  led  to  believe  that,  besides  the  Auroral 
limestones,  with  their  succeeding  argillites,  and  the  uncon- 
formably  superimposed  Silurian  (Oneida)  conglomerates 
of  the  North  Mountain,  there  are,  to  the  west  of  the  Lehigh 
River,  portions  of  two  intermediate  formations.  One  of 
these,  marked  by  red-colored  sand>it()nes,  conglomerates 
and  slates,  appears  to  be  the  same  w  itli  the  Upi)er  Taconic 
or  Cambrian  belt,  which  has  been  traced  by  II.  D.  Rogers, 
Mather,  Emmons,  Logan  and  the  writer,  with  some  inter- 
ruptions, from  New  Jersey  to  Canada,  along  the  great  Ap- 
palachian valley  (§  74,  03-90).  The  other  is  an  impure 
black  earthy  limestone,  becoming,  in  parts,  a  soft  thinly- 
laminated  llag-stone,  which  was  seen  lying,  at  moderate  an- 
gles, above  the  blue  limestone  of  the  valley,  not  far  from 
Copley,  and  was  then  supposed  to  belong  to  a  different  se- 
ries. It  is  apparently  the  same  with  the  Siluro-Canibrian 
(Trenton)  beds,  recognized  by  Prof.  Prime  in  that  vicinity. 

§  410.  The  evidences  adduced  in  these  pages  furnish 
abundant  proofs  of  tlie  unconformable  superposition  of  the 
Iluronian  to  the  Laurentian  series,  while  the  contrast  be- 
tween the  highly  disturbed  condition  and  nearly  vertical 
attitude  of  the  fomier,  and  the  broad  folds  and  gentler  dips 
of  the  Montalban,  in  so  many  regions,  have  long  since  been 
urged  by  the  writer  as  evidences  of  a  probable  stiatigrajihical 
unconformity  between  the  two.  As  regards  the  Taconian 
series,  its  apparent  relations  to  the  Montalban  in  Ontario, 
Maine,  and  North  Carolina,  and  the  frequent  absence  of  the 
latter  series  where  the  Taconian  rests  unconformably  upon 
Laurentian  or  Iluronian,  lead  us  to  conclude  to  a  want  of 
conformity  between  Mcmtalbau  and  Taconian.  In  like  man- 
ner, the  absence  of  the  Taconian  at  the  base  of  the  Cambrian, 
which,  in  so  many  jilaces,  reposes  directly  upon  the  Lauren- 
tian, or  upon  the  Iluronian,  indicates  a  great  stratigraph- 
ical  break  between  Taconian  and  Cambrian. 

§  417.  The  evidence  of  various  periods  of  disturbance, 


Jil 


:.  Hi 


21(5    E.       SI'KflAL    UKI'OFM'.      T.  STKIMJV    IirXT.   1875. 


IIIW' 


ni;iik('(l  by  discordanc*',  in  the  paleozoii^  strata  alon^  the 
Atlantic  belt,  have  been  pointed  out  in  §  241,  242,  where 
reasons  arc*  also  <5iveii  for  b<»lievinjjj  in  tlie  existence  of 
anotlier  such  ]»ei-iod  between  the  Cambrian  and  the  Silnro- 
Canibrian  (Ticnton-Loraine  sei-ics).  ^fr.  N[uiiay's  obser- 
vations near  Port-a-Poit  Hay,  in  Newfoundland,  furnish  a 
fiiitlici-  proof  of  this.  While  the  Cambrian  rocks  are  there 
affected  by  sliarp  folds  and  gi'eat  dislocations,  he  f'^ls  the 
limestones  holding'  a  Siluro-Cambrian  fauna,  near  o  be 

"('(►mparatively  undisturbed,"  ami  coucludes  ri;4"hi.y,  that 
the  movement  whi<'h  brouuht  thcci-ystalline  rocks  into  their 
position  of  aj)]>ai('ntly  unconformable  superposition  to  the 
foi'incr,  was  intermediate  between  the  two  ]»(M'iods  named. 
AVhile  w(^  dissent  fioni  his  view  of  tlui  orii^in  of  these  <'rya- 
talline  rocks,  and  believe  that  the  i)resent  geognostica I  re- 
lations ai'e  due  to  the  disruption  and  ujilifting  of  solid  rocks 
of  a  more  ancient  system,  ratiier  than  to  an  eruption  of 
igneous  matter,  about  "  the  age  of  theCliazy,"  the  evidence, 
in  either  case,  sIkjvvs  a  pei'i(/d  of  great  disturl)ance  of  the 
('and)iian  sti'ata  in  the  interval  above  indicated,  the  natural 
resiUt  of  which  would  be  a  want  of  couformitv  ^  ween 
these  and  the  succeeding  Sihiro-Cambrum.     ,^  377 

5^  418.  Before  passing  to  the  considei'ation  of  the  gvology 
of  Lake  Superior,  we  may  notice  the  presence  of  Iluronian 
rocks  in  Newfoundland.  In  his  report  for  18G8,  Mr.  Mur- 
ray announced  the  existence  of  a  series  of  liighly  contorted 
strata,  overlying  the  Laurentian,  and  tluMnstdves  overlaid 
unconformably  by  nearly  horizontal  sediments,  the  latter 
containing,  in  their  lower  portions,  a  Menevian  fauna,  and 
higher  up,  the  forms  of  the  Potsdam  or  Lingula  llag-group. 
This  mtermediate  series  was  declared  to  have  close  resem- 
blances with  the  Iluronian  of  the  great  lakes,  to  which  it 
was  at  once  referred  by  Mr.  Murray.  The  name  of  Cam- 
brian,  which  he  at  first  used  for  this  series,  as  synonymous 
with  Iluronian,  he  has  since  very  properly  rejected. 
(j5  359).  According  to  Di'.  Dawson,  who  has  examined  col- 
k^cticms  of  these  rocks,  they  are  very  similar  to  the  Iluron- 
ian of  southern  New  Brunswick,  so  that  we  are  constrained 
to  look  upon  them  as  a  porticjn  of  what  has  been  called  in 


IiriJoMAN  KOCKS  IX   XKWror.MU.AM). 


K.  '2\7 


noitlnvt'sfern  Newf(mii(U:iJi(l,  t\ut  "jiUj^ivd  Quebec  groui),'" 
whicli  we  have  already  relenvd  to  the  Iluroiiian  seiies. 

§  411).  This  lltirouiaii  series,  as  described  by  Mr.  Murray, 
is  loiind  in  the  soiitlieasten  |tart  of  Newi'omidiaiid,  and 
makes  lip  the  <'hier  jtait  of  the  peninsula  ol"  Avaloii.  Tlie 
strata  are  descrilted  as  consisting',  in  the  lower  poUions,  of 
greenstones  and  slaty  rocks,  often  epidotic  and  chloritic, 
with  qiiartzites,  coni!,lonierat<*s  and  jiispeiy  petrosilex. 
These  crystalline  rocks  have  a  thickness  of  many  th(»usand 
feet,  above  which,  in  ai>i)arent  conformity,  are  several 
thousand  fe<'t  of  sandstones  and  argillites,  liol<ling  organic 
rtinains  describ«'d  as  A^i>'i(J(ll(i  and  AvcnicoTiUs^  the  whole 
overlaid  unconforniably  by  the  Menevian  strata.  ^lej)ort 
on  tlie  Geology  of  Newfoundland  for  1{S<5S,  i)age  12;  (.'hem. 
and  Geol.  Essays,  page  410,  and  Geol.  Magazine  for  1877, 
page  25;]). 

As  evidence  of  the  gi*eat  erosion  to  which  this  region  was 
subjected  in  i)re-Cambrian  times,  Murray  notes  that  the 
nearly  horizontal  paleozoic  strata  above  named  an.'  found 
extending  alike  over  the  outcrop  of  the  Laurentian.  and 
over  the  basal  beds  '>C  the  nearly  vertical  lluronian  seric^s. 

§  420.  lluronian  ro'-ks  were  noticed  in  1870,  l)y  Mr.  Rich- 
r.nlson,  lying  to  the  ,  Ttli  of  Luke  St.  John  on  the  Sague- 
nay,  and  near  Lake  M.-itassini,  where  they  occup}'^  a  c<hi- 
siderable  breadth,  being  underlaid  by  the  Laurentian 
gneisses  and  limestones,  and  overlaid  by  the  horizontal  Si- 
lurian limestones  which  belong  to  the  basin  of  Hudson's 
Bay.  They  present  all  the  characters  of  the  Green  Mount- 
ain series.  In  1872,  Mr.  Walter  McOuat  passed  fiom  Lake 
Temiscaming,  on  the  Ottawa,  northward  to  Lake  Abbitib- 
be,  over  the  height  of  land,  and  crossed  a  great  area  of  simi- 
lar rocks,  described  as  closely  resembling  "tlu?  altered 
Quebec  groui)""  in  eastern  Canada,  and  as  including  diorites, 
with  chloritic,  micaceous  and  (>pi(lotic  strata,  rooling-slates, 
steatites,  chromiferous  serpentines,  magnetite  and  (.'oi»i)er 
ores.  (Geol.  Report  for  1870,  page  292,  ami  for  1872,  page 
115). 

§  421.  That  these  various  areas  of  lluronian  rocks,  whether 
found  in  the  Atlantic  belt,  or  lying  to  the  north  and  west 


^i- 


218  E.    spp:cial  report,     t.  sterry  hunt,  1875. 


of  it,  formed  parts  of  a  great  and  widely-spread  eozoic 
formation  is  clear,  and  it  is  a  question  whether  i)ortions  of 
it  may  not  exist  in  the  Adirondacli  region.  Tlie  writer  has 
found  in  the  drift,  in  the  rear  of  Westport,  in  Essex  county, 
New  York,  numerous  fragments  of  Iluronian  schists,  which 
may  reasonably  be  supposed  to  have  come  from  the  mount- 
ninous  region  of  the  interior. 

§  422,  In  tliis  connection  it  may  be  permitted  to  call  at- 
tention to  some  notes  by  Major  T.  B.  Broolvs,  published  in 
1872  (Amer.  Jour.  Sci.  Ill,  iv,  2?)  with  the  title,  "On  cer- 
tain Lower  Silurian  Rocks  in  fet.  Lawrence  county.  New 
York,  which  are  probably  okler  than  the  Potsdam  Sand- 
stones." Under  this  head  ho  lias  described  certain  strata 
found  with  the  specular  iron-ores  of  the  Keene  and  Cale- 
donia mines.  Immediately  under  the  ores,  is  said  to  be  a 
considerable  thickness  of  a  greenish  schistose  magnesian 
rock,  described  as  serpentine  by  Emmons,  beneath  which 
is  a  mass  of  crystalline  limestone,  several  hundinnl  feet 
thick,  which,  like  the  serpentine,  is  graphitic,  and  moreover 
contains  crystals  of  bronze-colored  mica.  It  includes  in 
its  lower  part  "irregular  beds  or  veins  of  granite,"  and 
is  underlaid  by  a  well-characterized  gneiss,  with  which  it 
is  conjectured  to  be  unconformable. 

Interposed  in  this  limestone  is  a  thin  bed  of  sandstone, 
and  a  similar  sandstone,  sometimes  conglomerate,  and  re- 
sembling the  beds  of  the  Potsdam,  overlies  the  iron-ore. 
These  strata,  including  the  great  mass  of  limestone,  are 
thrown  into  folds  with  a  northeast  and  southwest  strike, 
and  often  dip  at  high  angles.  They  have  all  the  characters 
of  the  Grenville  series  of  the  Laurentian,  from  which  there 
does  not  appear  to  be  any  good  reason  for  separating  them. 
The  associated  sandstone  beds  recall  the  similar  case  in 
Bastard,  Ontario,  described  in  §  28G. 

§  423.  As  regards  the  newer  series  of  crystalline  rocks, 
found  by  ^lurray  to  overlib  the  ancient  gneisses  around 
Lakes  Superior  and  Huron,  we  have  seen  that  Logan,  for  a 
long  time,  maintained  that  they  are  the  stratigrajihical 
equivalents  of  the  so-called  Volcanic  formations  of  Lake 
Superior,  wliich  are  characterized  by  amygdaloids  and  sand- 


CUPKIFEROUS  KOCKS  OF  LAKE  SUPERIOR.    E,  219 


Stones,  with  native  coi)per.  In  the  Esquisse  Geohnjique,  in 
1855,  as  well  as  in  the  geok)gical  map  accomi)anying  it,  the 
two  series  are  included  under  the  fommon  name  of  Hurt)n- 
ian,  then  first  used.  A  similar  view  was  defended  bv  Rivoc 
and  bv  Dawson,  in  1850  and  1857,  and  tlie  considerable 
mineralogical  and  lithological  dilVerences  between  the  two 
groups  were  ascribed  to  the  greater  amount  of  alteration  or 
metasomatic  change  which  the  former  had  undergone,  (§  141, 
142,  152-157). 

§  424.  In  1857,  however,  J.  D.  Whitney,  while  denying 
the  distinction  between  the  Iluronian  schists  and  the  un- 
derlying gneisses,  both  of  which  he  included  under  the 
common  name  of  the  Azoic  system,  declared  the  Volcai}ic 
or  native-copper  bearing  group  to  be  entirely  distinct  from 
the  Azoic,  and  superior  to  it  (§  158-160).  This  latter  con- 
clusion was  confirmed  by  the  examinations  of  Murray  in 
1859,  and  18(30,  (§  102)  and  in  1803,  in  the  Geology  of  Canada, 
the  name  of  Iluronian  was  confined  to  the  crystalline 
schists  which  make  the  upper  part  of  the  Azoic  system  of 
Whitney,  and,  from  their  metalliferous  character,  were  now 
sometimes  designated  the  Lower  Copper-bearing  series. 
The  Iluronian,  on  Lake  Superior,  was  now  said  to  be  "un- 
conformably  overlaid  by  a  second  series  of  copper-bearing 
rocks,"  which  was  the  Volcanic  format  ion  containing  native 
coxiI)er  (loc.  cit.  page  07). 

§  425.  As  regards  the  age  of  this  Upper  Copper- bearing 
series,  as  it  were  now  called  by  Logan,  we  have  seen  that 
Whitney  declared  that  it  ""cannot  be  separated  from  the 
Potsdam  sandstone  with  which  it  is  associated."  To  this 
horizon  he  referred  the  nearly  horizontal  sandstones  of  the 
region,  supposed  to  be  the  same  with  the  red  sandstones 
found  at  Sault  Ste.  Marie,  and  often  called  the  St.  Mary's 
sandstone.  The  observations  of  Mr.  Murrav  in  1859,  had 
however  slown  that  these  sandstones,  to  the  southeast  of 
SaultSte.  Marie,  are  overlaid,  conformal)ly,  by  a  fossiliferous 
limestone  belonging  to  the  base  of  the  Trenton,  from  which 
Logan  concluded  that  "'  the  underlying  sandsti  )nes  and  <  )tlier 
rocks  constituting  the  Upper  Copper-bearing  series  of  Lake 
Superior,  may  thus  represent  the  Chazy,  Calciferous  and 


I 

i 


220   E.       SPECIAL    REPORT.       T.   STERRY  HUNT,   1875, 

Potsdam  fornKitions,  and  be  equivalent  to  the  Quebec  group, 
and  tlie  black  slates  and  limestones  beneath."  This  sugges- 
tion was  put  forth  at  the  end  of  1800,  in  a  letter  to  Barrande, 
already  cited  (^5  201). 

§  420.  A  little  later  however,  in  Chapter  V  of  the  Geology 
of  Canada,  Logan  gave  reasons  for  believing  that  these 
sandstones,  then  regarded  as  of  the  age  of  the  Chazy  or  St. 
Filters  sandstone  (jj  27o,  270),  overlie  unccmi'orinably  the 
ti"ippean  and  conglomerate  rocks  with  which  they  had  been 
united  by  Whitney,  so  that  "the  coj^per-beai-ing  portions 
of  the  Lake  Su^jerior  rocks  might  reasonably  be  consider(?d 
to  belong  to  the  Calciferous  and  Potsdam  foiniations " 
(loc.  cit.  j)age  80).  Subse(piently,  in  discussing  the  Que- 
bec groux^,  and  the  crystalline  rocks  of  the  Green  Moun- 
tain range,  then  supposed  to  form  a  i^art  of  it,  it  was  said  : 
•'This  whole  series  of  rocks  however  occupies  a  strati- 
graphical  place  which  brings  it  to  the  horizon  of  the  Upjjer 
Copper-bearing  series  of  Lake  Superior.''  (Ibid,  page  2:^0). 
In  accordance  with  this  conclusion,  the  Upper  Copjier-bear- 
ing  I'ocks  were,  in  the  geological  maps  published  by  Logan 
in  IS(J4,  and  in  1800,  (^  44),  rei)resented  as  l)el()nging  to  the 
Quebec  group,  while  the  St.  Mary's  sandstone  was  referred 
to  the  Chazy  formation. 

§  427.  Reverting  now  to  the  more  ancient  rocks  of  this 
region,  we  have  seen(>$  140)  that  Foster  and  Whitney  recog- 
niz(Hl  besides  the  Azoic  schists,  called  Ijy  them  Metamoi'- 
phic,  a  great  group  of  Igneous  rocks,  ol"  different  ages,  in 
which  were  incbuled  granites,  viirlous  gi-eenstones  and 
hornblende  rocks,  and  the  crysialHne  iron-ores.  In  this 
they  were  not  singulai',  but  in  accordance  with  the  generally 
received  views  of  the  time.  Henry  D.  Rogei's  regarded  the 
greenstones,  epidotic  rocks  and  serpentines  of  the  Atlantic 
belt  as  igneous,  and  extended  tliis  view  to  the  magnetic 
iron-oi'es,  and  even  to  the  cpuirtz  veins  of  that  regicm  (jj  19, 
BO,  H2,  B7,  ;]9).  Fnnu(ms,  in  likc^  manner,  included  the 
granite,  hypersthene-i-ock,  ser[)entine,  limestones,  and  raag- 
netic  and  specular  oxyds  of  iron  of  northern  New  York, 
among  the  unstratilied  rocks  of  igneous  origin,  (§  8i)-87)  and 
Logan  held   the  same  view  with  regard  to  the  ILironian 


KIMBALL    OX    LAUHKXTIAX    AND    IirKOMAX.     E.  221 


gTt^enstones,  (^  141)  ;iltli()uu,'li  Rivot  denied  this,  and  nssorted 
that  they  were  altered  sediments,  a  view  wliich  he  extended 
to  the  traps  of  the  Upper  Copper-bearing  series  (§  loT). 

§  428.  The  arguments  of  Rivr>t,  from  the  relations  be- 
tween the  greenstones  of  the  okler  series  and  their  associ- 
ated schistose  rocks,  (§  152)  were  valid,  and  he  eri'ctl  only 
in  considering  them  the  sti-atigraphical  ecpiivalents  of  the 
gianidar  traps  and  amygdaloids  of  the  newer  series.  The 
studies  of  the  writer  in  the  years  following,  coniirming 
such  a  conclusion,  the  indigenous  character  of  these  and  sim- 
ilar greenstcmes,  and  other  feldsp  .riu(!  rocks,  was  maintained 
by  him  in  various  publicati(ms,  from  18r)8  (Chem.  and  Geol. 
Essays,  pages  4,  '•]',]).  Tliis  view  is  set  fortli  at  length  in 
Chapters  XIX  and  XX  of  the  Geology  of  Canada,  and 
further,  in  Conti-ibuticms  to  Lithology  (Amer.  Jour.  Sci.  II, 
xxxviii,  253).  The  writer  had  already  ])i-oposed  to  desig- 
nate by  the  term  ind/r/enous,  such  crystalline  rocks  as  have 
been  formed  ht  .S'/M,  in  contradistinction  to  tliose  Avhich 
have  been  intruded  into  tlieir  i)resent  places,  and  wliich 
Avere  called  e.volic  The  name  of  cndof/ciioKs  rocks  was 
prox)osed  for  a  third  class  of  nuneral  masses,  namely,  the 
c( )nci'eti()nary  vein-stones. 

§  429.  In  180.-)  appeared  an  impoitant  paper  on  the  Iron 
Ores  of  Marcxuette,  by  Dr.  J.  P.  Kimball  (Amei-.  Jour.  Sci.  II, 
xxxix,  21)1)  in  which  were  set  forth  his  studies  in  the  Azoic 
system  of  Whitney,  as  s<'en  in  northern  Michigan.  He 
showed  that  the  (>xtensive  belts  oi'  ran<^'es,  called  i)lutonic 
ii'ranites  ])v  Foster  and  Whitnev.  and  supiKtsed  bv  them 
to  lie  more  recent  than  the  Azoic  schists,  w<'re  really  indig- 
enous gneissic  rocks,  behmging  to  an  older  series,  which 
lie  pronounced  Laurentlan.  As  ivgards  the  overlying 
schists,  he  ccmlirmed  the  judgment  of  Murray  that  they  be- 
Iciig  to  the  Iluronian  series,  tlu^  greenstones  and  iron-ores 
of  which  were  also  declared  to  b(Miot  exotic  butiinligenous. 
Kimball,  at  the  same  time,  jHiinted  out  the  erioi- of  IJivot 
in  uniting  the  Upper  Copper-bearing  series  with  tlie 
Iluronian.  lie  also  nniognized  the  existence,  in  the  region, 
of  eruptive    granites   and    greenstones,    as    Murray    had 


m 


i 


222  E.       SPECIAL   REPORT.      T.    STERRY   HUNT,    1875. 

already  done  in  Canada,  but  declared  that,  though  abundant 
in  the  Laurentian,  they  were  very  rare  in  the  Huronian. 

§  430.  In  1809,  Dr.  Hermann  Credner  published  his  studies 
of  these  same  rocks  in  northern  Michigan.  He  followed 
Kimball  in  admitting  an  older  series  of  granitic  gneiss — 
the  Laurentian — which  was  unconformably  overlaid  by  the 
Huronian  rocks.  These  were  described  with  muc'  litho- 
logical  detail,  and  with  many  sections,  as  a  series  ol  ^uartz- 
ites,  limestones  and  red  iron-ores,  with  argillaceous,  clilor- 
itic  and  talcose  slates,  the  latter  two  associated  with  diorites, 
which  were  declared  to  be  not  eruptive  masses,  but  regularly 
interstratilied  members  of  the  series.  (Zeitschrift  d.  Deut- 
schen  geol.  Gesellschaf  t,  1869).  Credner  estimated  the  total 
thickness  of  the  series  at  about  20,000  feet,  which  agreed 
nearly  with  Murray's  previous  estimate  of  18,000  feet, 
(Geol.  of  Canada,  page  57). 

§  431.  In  1869,  Major  T.  B.  Brooks,  who  had  been  asso- 
ciated with  Prof.  R.  Pumpelly  (with  Credner  as  assist- 
ant, )  in  geological  explorations  in  the  northern  peninsula 
of  Michig[in,  commenced  for  the  State,  a  systematic  survey 
of  that  region.  The  results  of  their  labors  are  set  forth  in 
the  two  octavo  volumes  of  the  Geological  Survey  of  Michi- 
gan, published,  wdth  an  atlas  of  maps,  in  1873,  in  which  the 
iron-bearing  or  Huronian  rocks  are  described  l)y  Major 
Brooks,  and  the  Upper  Copper-bearing  series  by  Prof.  Pum- 
pelly. In  1869  and  1870  large  collections  of  rocks  from  the 
older  series  from  Michigan,  were  by  Prof.  Winchell,  then 
the  directt)r  of  the  geological  survey  of  that  State,  and  by 
Major  Brooks,  placed  in  the  writer's  hands  for  examination, 
some  of  the  results  and  conclusions  of  which  are  given  in 
the  following  extracts  from  a  letter  addressed  by  him  to 
Major  Brooks,  and  dated  Montreal,  Feb.  22,  1871  : 

§  432.  "I  find  you  are  waiting  for  my  conclusions,  some 
of  which  are  very  interesting  and  important.  You  remark 
about  the  mica-schists,  as  being  supposed  by  mo  wanting  in 
the  Huronian  of  Canada,  and  you  send  me  specimens,  Nos. 
1215,  bU54,  bll53.  I  have  for  some  time  past  recognized 
a  Mica-schist  series,  which  T  suppose  to  overlie  the  Huron- 


ian, in  fact  the  White  Mountain  series. 


* 


*     I  was 


MOXTALBAN   KOCKS   OF  MICHIGAN. 


E.  223 


therefore  deliglited  to  find  in  the  specimens  just  naiii<>d, 
well  characterized  White  Mountain  mica-schists,  holding 
garnets,  and  well-defined  crystals  of  staurolite,  while  the 
peculiar  knotted  mica-schist  is  not  less  characteristic. 
These  rocks  are  abundantly  spread  to  the  north  of  Lake 
Superior,  as  last  year  s  collections  [of  the  Canada  Survey] 
show  me,  and  though  I  have  been  not  able  to  fix  their  re- 
lations to  the  Iluronian  diorites,  talcose  schists,  iron-ores, 
etc.,  I  conclude  from  the  facts  seen  near  Portland,  in  Maine, 
and  those  described  by  Rogers,  in  Pennsylvania,  that  they 
are  overlying  rocks,  and,  in  some  cases  at  least,  v.nconform- 
ably  so.  You  say  that  they  are  the  youngest  rocks  in  the 
region  belonging  to  the  Iluronian.  I  susj^ect  that  they  be- 
long to  a  younger  series."  "I  distinguish  three  crystalline 
gneissic  series  :  I.  Laurentian,  (not  to  speak,  for  the  present, 
of  the  Labradorian) ;  II.  Iluronian  ;  III.  Terranovan  [Mon- 
talban],  these  being  respectively,  in  the  United  States,  the 
rocks  of  the  Adirondacks,  the  Green  Mountains,  and  the 
White  Mountains.  I  hope  you  will  be  able  to  decide  whether 
there  is  any  want  of  conformity  between  II  and  III.  I 
should  mention  that  in  Hastings  county,  Ontario,  the  three 
series  are  all  represented,  and  there  is  apparently  a  strati- 
graphical  break  between  each." 

"I  have  thus,  I  think,  ■*  *  touched npon  the  principal 
points  of  interest  in  your  collections,  of  which  the  two  chief 
facts,  are  the  close  resemblance,  and  I  believe  identity,  of 
the  great  iron-bearing  dioritic,  talcose  series  with  the  Green 
Mountain  series,  IT,  and  the  equally  close  resemblance  of 
the  rocks  1215  and  lir)l-lin4,  with  the  AVhite  Mountain 
series  III,  which  I  conceive  to  belong  to  a  higher  hoii/on."' 

§4^3.  "The  collections  sent  last  '■'"  ^  *  from  Smith's 
^fountain  and  vicinity,  are  also  members  of  what  I  regard 
as  series  III,  and  quite  unlike  the  Iluronian  type,  II."  [Here 
follow(Hl  details  of  thirty-nine  specimens.]  "Many  of  these 
rocks  are  very  quartzose.  Feldspar  is  occasionally  devel- 
oped, giving  a  gneiss  A\hicli  is  seen  in  *  *  and  *  * 
in  which  the  white  cleavable  orthoclase  is  developed  so  as 
to  form  a  porphyritic  gneiss." 

§  434.    "A  word  about  felsites.     I  have  a  large  si)ecim('U 


I 

4 


I 


■  I 

il 

ST 

'! 


i''- 


224  E.     SPKf'lAL    REPORT.      T.    STP^RRY    IICXT,    1875. 

of  conulomemte,  with  native  copper,  from  tlie  All)!iin^  & 
Boston  Miniiiii;  Co.'s  i)roperty,  brought  me  by  Mr.  Macfar- 
lane,  who  hus  brielly  desci'ibed  it  in  the  CTeoh)gical  Report 
of  Canada  for  18G:}-(J(5,  pa,i.?e  156.  Tlie  poi-phyry  boulders 
and  pebbles  of  which  he  there  speaks,  are  line  examples  of 
th(3  felsite  of  Avdiich  1  wrote  you,  better  named  eurite  or 
peti'osilex,  and  i)assiui;-  into  quartziferous  porphyry.  ■*  * 
What  is  the  source  of  the  boulders?  I  suspect  it  will  be 
found  in  the  lower  part  of  the  Uuronian  system,  for  it  has 
the  typical  character  of  tlie  Uuronian  eurites,  as  seen  along 
the  east  coast  of  N(?w  England,  etc.,  from  Rhode  Island  to 
Newfonudland.  and  also  to  the  north  of  Lake  Ontario.  Do 
you  know  any  such  rock  i/i  .svYii,  and  have  you  jierhaps 
deeuKHl  it  erui)tiver' 

§  435.  The  above  conclusions  as  to  this  overlying  gneiss 
and  mica-schist  series,  was  soon  after  made  known  l)y  the 
writer,  in  his  address  in  August.  1871,  (§  347),  where  it  was 
said  that  the  schists  both  of  the  Green  Mountain  and  the 
White  Mountain  seiies  '*ai'e  represented  in  Michigan,  as  ap- 
pears by  tin?  n^'ent  collections  ol'  ^lajor  Brooks  '-^  * 
kindly  placed  in  my  hands  for  examination.  He  infoi-ms 
me  that  thes(?  latter  schists  are  the  highest  of  the  crystal- 
line strata  in  the  northern  peninsida."  (Chem.  and  Geol. 
Essays,  page  274). 

§  436.  Tlie  above  collections  were  from  the  Marquette  re- 
gion, and  the  schists  referred  to  the  White  oMountain  series 
were  designated  by  Brooks  in  his  report,  in  1873,  as  division 
No.  XIX,  described  as  "a  formation  of  great  extent  and  in- 
terest," "tlie  youngest  member  of  the  series"  of  Uuronian 
rocks,  and  "one of  the  thickest"  in  the  u])per  jxminsula of 
Michigan.  It  is  often  v(>ry  silicious  and  micaceous,  and  con- 
tains besides  black  horiiblen<le,  staurolite  and  gai'net,  ciys- 
tals  of  andalusite  (loc.  cit.  i)ages  113,  130).  In  the  same 
report,  in  the  account  of  the  Menomenee  regi(m  in  Michigan, 
was  descrilxnl  (page  17."))  "a  large  outcrop  of  gneiss,  with 
thin  layers  of  granite,  "  adjoining  "  a  great  hornblendic  and 
mica-schist  sei'ies,  "  and  pres<>nting  a  Laurentian  as])ect, 
thcnigh  "conformably  oveilying  rocks  unmistakably  Uuron- 
ian." 


BROOKS   ON   TUE   MONTALBAN   OF   MICHIGAN.     E.  225 


§  437.  In  his  subsequent  examinations  of  the  rocks  of 
northern  Wisconsin,  to  the  soutli  and  west  of  the  ^lenome- 
nee  river,  Brooks  found  in  the  Penokie  region  a  great  area 
of  similar  gray  gneisses,  often  granitoid,  associated,  as  be- 
fore, with  hornblendic  and  mica-schists.  These  latter  he 
regards  as  the  equivalents  of  division  XIX  of  the  Miiiquette 
region,  and  at  the  same  time  suggests  that  some  of  the 
granitic  rocks  of  the  latter  area  may  be  identical  with  what 
he  calls  the  Penokie  granitoid  formation.  These  later 
observations  and  comparisons,  were  set  forth  by  Brooks  in 
1875,  in  a  paper  on  The  Youngest  Iluronian  Rocks,  etc. 
(Amer.  Jour.  Sci.  III.  xi,  20G)  under  which  head  he  includes 
the  three  areas  of  granitoid  gneisses,  with  their  associated 
hornblendic  and  micaceous  schists.  From  their  similar 
lithological  characters,  the  entire  absence  from  them  of  ^he 
iron-ores,  which  abound  in  what  he  calls  the  middle  and 
lower  portions  of  the  Iluronian,  and  from  their  geognostical 
relations  alike  to  these  and  to  the  unconformably  overlying 
UiDper  Copper-bearing  series,  Brooks  concludes  that  the 
granitoid  formation  must  be  regarded  as  the  youngest  mem- 
ber of  the  Huronian  series. 

§  438.  It  will  l)e  noticed  that  the  immediate  associate  of 
this  granitoid  formation  in  each  of  the  three  districts  is  the 
peculiar  micaceous  and  hornblendic  schists,  XIX,  and  it 
was  these  schists,  and  the  granitoid  gneisses,  from  the  Mar- 
quette region,  which  the  \vi'iter,  so  long  ago  as  1871,  re- 
ferred to  the  White  Mountain  or  Montalban  series,  then,  as 
now,  placed  by  him  above  the  Huronian — a  testimony  to 
the  value  of  lithological  characters  in  geology.  In  his 
paper  already  quoted,  Brooks  remarks  on  this  point:  "I 
would  anticipate  the  objections  which  many  will  make  to 
attaching  much  weight  to  lithological  evidences  in  deter- 
mining the  age  of  formations  one  hundred  miles  apart,  by 
repeating  that  the  staurolitic  mica-schist  formation  (  XIX ) 
maintains  its  mineralogical  characters  for  over  one  lialf  that 
distance."  For  further  notices  of  these  gi'anitoid  gneisses 
of  the  Montalban  series,  see  Chem.  and  Geol.  Essays,  i^ige 
188,  244.  These  rocks  have  certain  lithological  resemblances 
to  the  gneisses  of  the  Laurentian,  but  their  inherent  tliffer- 

[E.  15.  J 


226   E.       SPECIAL    REPOUT.      T.  STEHRY  HUNT,  1875. 


ences,  not  less  than  tlie  character  of  the  associated  schists, 
suffice  to  distinguish  them. 

§  439.  Tlie  greenstones  of  the  Huronian  of  Lake  Superior, 
have  been  generally  described  as  diorites,  and  the  correct- 
ness of  this  designation  is  confirmed  by  the  microscopic 
studies  of  Julien,  and  of  Wright,  who  find  them  to  be  es- 
sentially composed  of  a  triclinic  feldspar  and  amphibole, 
(hornblende)  frequently  with  chlorite.  According  to  the 
former,  some  of  them  "  may  possibly  contain  pyroxene  in 
place  of  amphibole."     (Geol.  of  Micliigan,  1873,  II,  43). 

§  440.  In  the  writer's  account  of  the  similar  rocks  from 
the  Green  Mountain  range  in  Canada  they  were  desciibed 
as  rocks  composetl  in  part  of  triclinic  feldspars.  "Through 
an  admixture  of  hornblende,  these  feldsjiar-rocks  pass  into 
diorite,  in  different  varieties  of  which  the  one  or  the  other 
mineral  jiredominates.  *  *  *  These  compound 
rocks  are  often  so  finely  granular  as  at  first  sight  to  appear 
homogenecjus  ;  at  other  times  they  are  rather  coarse-grained, 
and  sometimes  porphyritic  from  the  presence  of  large  crys- 
tals of  feldspar.  *  *  The  imbedded  hornblende- 
crystals  are  occasionally  of  considerable  size,  and  darlv- 
green  in  color.  In  some  places,  the  hornblende  is  replaced 
by  pyroxene  or  diallage." 

After  describing  the  relations  between  the  steatites,  dial- 
lage-rocks  and  serpentines,  which  often  accompany  these 
feldspathic  rocks,  it  was  said:  "Both  the  serpentines  and 
the  diorites  sometimes  become  schistose,  and  the  latter  seem 
to  graduate  into  chloritic  slates  nnd  epidosites,  on  the  one 
hand,  and  into  hornblende  slates  on  the  other,  so  that  it  is 
difficult  to  resist  the  conclusion  that  the  whole  series  of 
rocks  just  named,  from  diorites,  diallages,  and  seri^entines, 
to  talcs,  chlorites  and  epidosites,  have  been  formed  under 
similar  conditions."  (Geok)gy  of  Canada,  pages  602,  012). 
See  further,  Amer.  Jour.  Sci.  II,  xxxvii.  2G6. 

§441.  A  belt  of  Ilaronian  rocks  is  found  in  southern 
Connecticut,  to  the  west  of  New  Haven.  These  were  de- 
scribed by  the  late  Prof.  Silliman,  more  than  half  a  century 
since,  as  "primitive  greenstones,"  and  later,  by  Percival, 
as  a  "chloritic  formation."     In  1870,  J.  D.  Dana  published 


HURONIAN   GREEX8TONKS. 


E.  227 


some  notes  on  these  rooks,  describing  the  association  of  tlie 
greenstones  with  chhjritic  schists,  and  with  serpentines, 
and  adopting  the  previously  announced  conchision  of  the 
writer,  tliat  "  their  common  metamorphic  origin  cannot  be 
questioned." 

Tliese  rodvs  were  at  tliat  time  submitted  to  an  examination 
by  Mr.  George  W.  Hawes,  who  found  two  of  tlu?m  to  be 
identical  in  chemical  composition,  respectively,  with  an 
exotic  dolorite  and  an  exotic  diabase,  which,  a  few  mik^s  dis- 
tant, in  the  vicinity  of  New  Haven,  break  through  the 
mesozoic  sandstones.  These  exotic  masses  moreover  closely 
resemble  in  aspect  the  indigenous  rocks  in  question,  which 
were  accordingly  described  as  aggregates  of  labradorite  and 
pyroxene,  (with  some  titanic  iron)  with  the  addition,  in  one 
variety,  of  a  portion  of  chlorite  (Amer.  Jour.  Sci.  Ill,  xi, 
119  and  122). 

§  442..  Dana,  on  account  of  this  apparent  identity  in 
lithological  characters,  pi-oposed  to  call  these  indigenous 
or  metamorp hie  greenstones,  metadolerite  and  metadiabase. 
Such  a  nomenclature  is  however  based  on  a  misconception 
of  the  province  of  lithology,  which  is  distinct  from  that  of 
geognosy.  In  the  language  of  the  author,  in  18G4,  the 
same  mineralogical  aggregate  "may  occur  both  as  an  in- 
digenous and  an  exotic  rock,  and  different  portions  of  the 
same  mass  may  be  seen,  by  different  observers,  under  such 
unlike  conditions  that  one  may  regard  it  as  indigenous,  and 
the  other  with  equal  reason,  set  it  down  as  intrusive." 
"To  the  litliologist,  who  examines  rocks  without  reference 
to  their  geological  reflations,  the  question  of  the  exotic  or 
indigenous  character  of  a  given  rock  is,  in  most  cases,  one 
altogether  foreign,  and  one  which  can  frequently  be  de- 
cided only  by  the  geologist  in  the  field.''  (Amer.  Jour.  Sci., 
II,  xxxvii  2.")4).  These  remarks  remain  essentially  true  to- 
day, especially  for  many  granitic  and  euritic  or  petrosilici- 
ous  masses,  although  the  use  of  th(»  microscope  now  enables 
one,  in  many  cases,  to  distinguish  between  the  indigenous 
rock  and  its  exotic  representative,  as  in  the  case  of  the  di- 
orites  belonging  to  the  two  classes. 

§  443.  It  should  be  said  that  Mr.  Hawes,  by  microscopic 


m 


228  E.      RPECIAL   REPOIIT.      T.  STEllIlY  HUNT,  1875. 

examinations,  has  since  found  tliat  the  indigenous  green- 
stones noticed  by  Dana,  are  really  diorites,  in  one  case  con- 
taining some  chlorite.  (Ibid,  III,  xv.,  210.)  The  further 
extended  studies  (as  yet  unx^ublished)  by  Mr.  Ilawes,  of  the 
Iluronian  greenstones  of  New  Hampshire  have  yielded  sim- 
ilar results,  and  show  that  these  rocks,  also,  are  essentially 
diori(i(!  in  character,  consisting  chielly  of  an  admixture  of 
a  plagioclase  feldspar  with  hornblende,  rarely  containing 
grains  of  pyroxene,  and  often  becoming  chloritic,  as  long 
since  described  by  the  writer.  From  the  similarity  in 
chemical  comj^osition,  and  the  intimate  mineralogical  rela- 
tions between  hornblende  and  pyroxene,  it  seems  highly 
probable,  that  in  accordance  with  the  theory  of  exotic 
rocks  maintained  by  the  writer,  (Chem.  and  Geol.  Essays, 
4,  9,  44),  the  exotic  dolerites  and  diabases  of  the  New  Haven 
mesozoic  are  but  displaced  and  modilied  greenstones  of  the 
underlying  Iluronian  series. 

§  444.  As  regards  the  lithology  of  the  Iluronian  of  north- 
ern Michigan,  it  may  be  remarked  that  although  Julien 
found  no  well-defined  serpentines,  the  writer  examined 
some  years  since,  specimens  of  both  massive  and  fibrous 
serpentine,  believed  to  be  from  the  falls  of  the  Sturgeon 
river,  received  from  Dr.  Rominger  of  the  Michigan  geologi- 
cal survey,  which  had  the  characters  of  the  typical  ser- 
pentines of  the  Iluronian  of  the  Atlantic  belt.  Allusion 
should  here  be  made  to  the  serpentine  of  Presqu'isle,  ana- 
lyzed by  Whitney.  (Geol.  of  Lake  Superior,  II,  92).  The 
writer  has  found  some  of  the  serpentine  rocks  of  this  re- 
gion to  be  chromiferous. 

It  is  of  interest  to  note  the  occurrence  of  large  quanti- 
ties of  a  carbonaceous  argillite,  noticed  by  Brooks  in  sev- 
eral localities  in  the  Huronian  of  Lake  Superior,  which  has 
a  black  streak,  burns  white  before  the  blow-pipe,  and  yields 
over  twenty  per  cent,  of  carbon.  (Geology  of  Michigan, 
I,  part  1,  116). 

§  445.  In  the  volume  just  quoted,  the  Upper  Copper-bear- 
ing series  was  described  as  consisting  of  interbedded  sand- 
stones, conglomerates,  melaphyres  and  amygdaloids,  dip- 
ping northward  at  an  angle  of  fifty  degrees  or  more,  and  over- 


i  1 


PEI'UOSILEX    UOCKS   OF   LAKE  SUPEUIOK.         E.  229 

laid  nnconformably  by  tlie nearly  horizontal  St.  Mary's  sand- 
stonos,  in  whicli  Mr.  Alex.  Agassiz  found,  near  Ilongliton, 
abundant  pebbles  of  melaplu-re  and  conglomerate,  from 
the  underlviug  series.  No  dirtn^t  estimate  of  the  vohime  of 
these  latter  rocks  was  attempted,  though  it  was  said  ''they 
have  a  thickness  measured  by  miles,  a  tliickness  which  they 
exhibit  wherever  they  are  known,  at  points  hundreds  of  miles 
apart  on  the  north  and  south  shore"  of  Lake  Superior.  As 
regards  the  age  of  this  Upper  Copper-bearing  series,  it  was, 
at  tliis  time,  by  M(^ssrs.  Brooks  and  Pumpelly,  declnred  to 
have  been  "  formed  before  the  tilting  of  the  Iluronian  beds, 
upon  which  it  rests  conformably,"  and  to  be  probablj'' 
more  closely  related  in  age  to  those,  than  to  the  overlying 
paleozoic  sandstones.     (Ibid.  I,  part  2,  pages  1-G). 

§  440.  The  reader  is  now  prepared  to  understand  the 
significance  of  the  question  raised  by  the  writer  in  1871,  as 
to  the  existence  of  the  felsite  or  petrosilex-porphyries,  in 
place,  in  the  Lake  Superior  region  ;  since  tliese  rocks,  which 
had  then  been  found  by  him  to  belong  to  the  Iluronian 
series,  (§  363-372),  occur  in  pebbles  in  the  conglomerates 
of  the  Upper  Copper-bearing  series,  (§  434).  Besides  the 
locality  already  mentioned,  the  great  cupriferous  bed  of  the 
Calumet  and  Hecla  mine  is  a  remarkable  example  of  a  rock 
made  up  almost  wholly  of  the  ruins  of  these  joeculiar  petro- 
silexes.  In  1872,  as  already  described,  (§  372),  he  found 
these  rocks,  in  siM^  on  the  north  shore  of  Lake  Superior, 
and  was  moreover  led  to  suspect  that  both  the  banded 
jaspery  quartzose  porpliyry  of  the  P(U'cux)ine  Mountains,  de- 
scribed by  Foster  and  Wliitney  as  of  igneous  origin,  (§  151), 
and  the  similar  rocks,  said  to  occur  at  Mount  Houghton  in 
the  southern  range  of  Keweenaw  Point,  (§  150);  regarded  by 
the  same  observers  as  an  altered  sandstone  of  the  Upper 
Copper-bearing  series,  to  which  they  referred  tliis  soutliern 
range,  known  as  the  Bohemian  Mountains. 

§  447.  The  lithological  characters  of  this  southern  belt,  as 
alreadv  described,  are  however  verv  like  those  of  the  Huron- 
ian,  and  widely  different  from  those  of  the  more  nortlun-n 
belts,  (§  149)  which  are  the  typical  Upper  Copper-bearing 
rocks.     This  Avas  noticed  hy  Dr.  Charles  T.  Jackson,  who 


230   E.      SPECIAL   KEPOllT.      T.  STKKUY  HUNT,  1875. 


jft^m 


r 


remarked  that  the  labmdoritic  fjreenstone  of  tlie  south- 
ern portion,  near  Lake  Labelle,  diirers  from  tliat  of  tlie 
nortliern  ranges,  in  being  a  crystalline  rock.  He  adds  witli 
regard  to  it :  "If  the  rock  were  not  connected  with  the  more 
hornblcndic  traps,  and  in  the  same  line  of  diiecti(m,  burst- 
ing through  the  same  kind  of  sandstoii"  strata,  I  shouhl 
feel  disposed  to  regard  it  as  of  more  ancient  origin.  Indeed, 
I  am  far  from  being  satisfied  that  it  is  not  more  .incient,  for 
the  limited  exposure  of  the  rocks  does  not  allow  any 
geologist  to  be  too  conlident  as  to  its  age."  (Report  to  31st 
Congress,  1849,  Exec.  Doc.  No.  I,  i)art  iii,  page  473). 

Mr.  Ernest  Gaujot,  whose  skill  and  long  experience  as  a 
geological  observer  and  a  mining  engineer,  in  this  region, 
give  much  weight  to  his  opinion,  informs  the  writer  that  he 
has  always  believed  the  Bohemian  Mountain  range  to  belong 
to  an  older  series  than  the  copper-bearing  rocks  to  the  north 
of  it. 

§  448.  The  reader  who  remembers  that  the  Upper  Copper- 
bearing  series  had  already,  in  1803,  been  declared  by  Logan 
to  rest  unconformubly  upon  the  Iluronian,  (§  424)  along  the 
north  shore  of  Lake  Superior,  miglit  dfem  this  an  answer 
to  the  views  of  Brooks  and  Pumpelly,  who,  in  1873,  still 
supposed  the  two  conformable,  and  nearly  related  in  age. 
As  will  be  shown  farther  on,  lunvever,  the  writer,  from  his 
studies  on  the  north  shore,  in  1872,  was  led  to  conclude  that 
the  rocks  there  overlying  the  Huronian,  of  which  they  con- 
tain fragments,  are  not,  as  was  supposed  by  Logan  and  by 
Murray,  a  lower  division  of  the  Upper  Copper-bearing 
series,  but  belong  to  a  distinct  formation,  of  indetermined 
age.  He,  however,  found  that  the  conglomerites  of  the 
tyi)ical  Ujiper  Copper-bearing  series  at  Mamainse  include, 
as  already  described  (§  150),  rounded  masses  of  tl' 
stones  and  chloritic  schists  of  the  Iluronian,  :is  we' 
characteristic  gneisses  and  mica-schists  of  aii 

thus  showing  a  stratigraphical  break  betwei       liese        stai 
line  schists  and  the  Upper  Copper-bearing  series  ;  ;  iid  con- 
firming the  conclusion  already  reached  from  the  oc>  urrence 
of  petrosilexes,  believed  to  be  Iluronian,  in  the  conglomerates 
of  the  same  horizon,  in  the  Keweenaw  peninsula. 


THK    KKWEEXIAN    SERIES. 


E.    231 


§  449.  The  great  serios  of  highly  inclined  Hnndstones  and 
conglonjerates  which,  with  intcrstrafitied  trappcan  masses, 
constitute  the  cui)i'irei(nis  rorination  of  this  region,  and 
are  clearly  distinct  both  from  the  overlying  sandstones 
and  the  underlying  Iluroi'.ian  sciusts,  required  a  distin- 
guishing name.  Hence,  the  writer,  in  his  atldress  on  the 
Geognostical  History  of  the  Metals,  before  the  American 
Institute  of  Mining  Engineers,  in  February,  187:5,  designated 
it  tile  Keweenaw  gronp,  and  snggested  that  its  included 
native  copper  had  probably  been  derived  from  the  oxy- 
dized  and  dissolved  coj)per-sulphurets  of  the  Huronian, 
(Trans,  etc.,  I.  330,  341).  In  March  187."),  Major  Brooks,  who 
had  apparently  overlooked  the  above  announcemeut,  but 
had  himself,  in  the  meantime,  arrived  at  the  conclusion  that 
there  exists  a  stiiitigraithical  break,  and  a  niarkfjd  distinc- 
tion, between  the  Huronian  schists  and  the  Upper-Copper- 
bearing  group,  declared  that  the  latter  constitute  "a  distinct 
and  independent  series,  marking  a  definite  geological  pe- 
riod," and  proposed  for  its  designation  the  adjective  Ke- 
w^eenawian.  (Amer.  Jour.  Sci.  III.  xi,  2I</).  For  this,  the 
writer,  while  recalling  his  own  conclusions,  and  the  name 
of  Keweenaw  series,  given  two  years  eai-lier,  suggested  the 
more  euphonious  word,  Kevveenian.  (Harper's  Annual 
Record,  1870,  page  xcv). 

§  4r)().  Late  researches  in  Wisconsin  have  thrown  much 
additional  light  on  the  geology  of  the  Lake  Superior  region, 
and  the  results  are,  in  part,  set  forth  in  the  volume  on  the 
geology  of  the  State,  pul)lished  in  1877.  The  Primary  or 
eozoic  rocks  of  Wisconsin  are,  by  Prof.  Roland  D.  Irving, 
divided  into  an  older  gneissic,  Laurentian,  series,  and  an 
unconformablv  (n'erlying  series,  regarded  by  him  as  Huron- 
ian,  and  including  a  great  development  of  the  petrosilex- 
porphyries.  These  latter  have  there  been  chiefly  studied 
to  the  south  of  the  great  Primary  area,  in  a  region  where 
n I mierous  ridges  of  the  underlying  rocks  appear  through 
the  horizontal  paleozoic  sandstones,  ' '  protruding,  but  not  in- 
truded, "  recalling  the  similar  outcrops  in  southeastern 
Missouri  (^373). 

§  4i")l.  These  ridges,  which  are  naturally  the  more  resist- 


232   E.      SPECIAL   REPORT.      T.  STERRY  IIUKT,  1875. 


ing  portions  of  the  eroded  eozoic  series,  consist,  in  large 
part,  of  qiiartzites,  massive  and  vitreous,  or  slaty,  and  inter- 
laininated  with  soft  aluminous  schists,  which  have  been 
called  talcose.  These  various  strata,  which  are  highly  in- 
clined, and  evidently  belong  to  a  series  of  great  thickness, 
were,  by  Percival,  called  "altered  Potsdam,"  and  by  Alex- 
ander Winchell,  Lower  Potsdam,  but  in  18G2,  were,  by  Prof. 
James  Hall  referred  to  the  Huronian  series,  with  which  they 
are  classed  by  Prof.  Irving.  The  quartziferous  porphyries, 
sometimes  becoming  schistose,  and  interbedded  with  unctu- 
ous schists,  are  found,  either  alone,  or  conformably  suc- 
ceeding the  quartzites,  the  strata  having  a  steep  northward 
dip.  In  one  section,  on  the  Baraboo  River,  the  total  thick- 
ne'-'s  of  these  rocks  exposed  is  about  5,000  feet,  including 
a  brtudth  of  about  GUO  feet  of  the  porphyries,  which,  in 
another  section,  are  estimated  at  not  less  than  3,200  feet  in 
thickness.     (Geology  of  Wisconsin,  1877,  pages  501-521). 

These  rocks,  from  the  lithological  descriptions  given,  in- 
cluding the  microscopic  characters,  and  the  results  of  chem- 
ical analysis,  are  evidently  identical  with  the  orthofelsites, 
or  petrosilex-porphyries,  previously  described  by  the  writer 
as  characteristic  of  the  Huronian  series  along  the  Atlantic 
coast,  in  the  Soiali  Mountain  in  Pennsylvania,  and  in  Mis- 
souri. They  are  the  same  with  those  which  were  discovered 
by  him  on  the  north  shore  of  Lake  Superior,  and  which 
enter  so  largely  into  the  cupriferous  conglomerates  of  the 
Keweenian  series,  on  the  south  shore  of  the  lake. 

§  452.  The  volume  just  cited  does  not  give  the  late  ob- 
servations of  Mr.  E.  T.  Sweet  of  the  ge(jlogical  survi^y  of 
the  State,  which  he  has  set  forth  in  the  Transactions  of  the 
Wisconsin  Academy  of  Science  for  187G,  (pages  41-55),  in 
a  paper  on  the  Geology  of  Northern  Wisconsin.  The  Ke- 
weenian series,  as  was  shown  by  Foster  and  Whitney,  oc- 
cupies a  great  synclinal  on  Lake  Superior,  which  is  traced 
uninterruptedly  into  Bayfield  county,  Wisconsin,  a  distance 
of  more  than  two  hundred  miles,  and  with  a  thickness 
which,  according  to  Mr.  Sweet,  is  often  over  00,000,  and 
never  less  than  20,000  feet.  Beyond  this,  it  is  followed, 
with  some  interrui^tions,  for  one  hundred  miles  further  to 


CAMBRIAN    SANDSTONES  OF   LAKE  SUPERIOII.    E.  "J'^'S 


the  south-west,  extending  across  the  State  of  Wisconsin, 
and  into  Minnesota,  though  with  a  diminished  volume,  from 
the  thinning-out  of  the  conglomerates,  and  frcm  erosion. 
The  amygdaloids  of  this  series  are  seen  at  the  Dalles  on  the 
river  St.  Croix,  where  they  yield  native  copper.  These 
rocks,  at  this  locality  were,  by  Owen,  regarded  as  eruptive, 
and  newer  than  the  adjacent  sandstone,  but  Sweet  makes 
it  clear  that,  on  the  contrary,  the  lower  beds  of  the  sand- 
stone rest  horizontally  upon  the  trappean  rocks,  and  are 
made  up  in  part  of  their  ruins.  These  basal  sandstones  are 
shown,  by  the  presence  of  LliigiUepis  plnncvformls  and 
Oholella  lyol'da^  to  belong  to  the  Potsdam  sandstone  of  the 
region. 

§  453.  These  sandstones,  wdtli  their  interstratified  and 
overlying  magnesian  limestones,  constituting  in  this  region 
a  series  of  about  1.000  feet  in  thickness,  beneath  the  St. 
Peter's  or  Chazy  sandstone  have  already  been  noticed, 
(§270-278)  and  are  geograph'cally  distinct  from  the  sand- 
stones which,  along  the  sou  the  'u  shore  of  Lake  Superior,  over- 
lie unconformably  the  Kewee  Jan  series.  Mr.  Sweet  (loc.  cit. 
page  49)  remarks  :  "  There  is  no  known  locality  west  of  Ke- 
weenaw Point  where  the  Lake  Superior  sandstone  and  the 
Potsdam  ot  tno  Mississix^pi  valley  are  not  separated  by  many 
miles." 

Under  the  name  of  Lake  Superior  sandstones,  Mr.  Sweet, 
following  Dr.  Rominger,  includes  the  nearly  horizontal  sand- 
stones which  extend  along  the  whole  southern  shore  of  the 
lake,  including  what  has  elsewhere  been  spo!>:en  of  as  the 
St.  Mary's  sai.dstone.  This  was,  in  18G3, 1'egarded  by  Logan 
as  probably  of  the  age  of  the  St.  Peter's  or  Chazy  sandsfone 
of  the  Mississippi  valley,  (§  10."))  and  colored  as  such  in  the 
geological  maps  of  18G4  and  18(50  (§44). 

§  454.  We  have  seen  that  Hall  long  since  observed,  in  some 
beds  between  these  sandstones  and  the  overlying  mass  of 
Trenton  limestone,  strata  containing  organic  remains  of  the 
Chazy  formation.  Dr.  Rominger  has  since  found,  through- 
out the  northern  peninsula  of  Michigan,  at  this  horizon,  a 
series  of  beds,  which,  from  their  oi'gani(!  remains,  lie  declares 
to  reijresent  both  the  Chazy,  and  the  Calciferous  formation, 


234  E.      SPECIAL   REPORT.      T.    STERRY   HUNT,   1875. 


of  the  New  York  series,  leaving,  according  to  him,  no  alter- 
native but  to  regard  the  underlying  sandstones  as  the  equiv- 
alent of  the  Potsdam."  (Geol.  of  Michigan,  1873,  Vol.  I, 
pages  71,  80). 

These  intermediate  beds  are  partly  calcareous  or  dol- 
omi'ic,  and  partly  silicious,  consisting  of  "small  perfect 
quartz  crystals,  with  glistening  facets,  and  sharp,  unworn 
angles."  Mixed  with  these,  ai'e  numerous  oolitic  silicious 
globules,  and,  in  some  cases,  masses  of  banded  chalcedony, 
the  whole  recalling  the  observations  made  regarding  the 
silicious  beds  of  the  Potsdam,  in  other  localities  (§  2G9). 

§  455.  These  intermediate  beds  have  a  variable  thickness, 
and  in  one  case  measure  nearly  one  hundred  feet.  The 
thickness  of  the  underlying  sandstones,  to  the  east  of  the 
co]3per- region,  where  they  rest  upon  the  older  crystalline 
rocks,  does  not  exceed  tliree  hundred  feet,  but  to  the  west- 
ward, it  is  not  easy  to  fix  the  limit  between  them  and  the 
older  sandstones  which  form  the  upper  portion  of  the  Ke- 
weenian  series,  and  are  designated  by  Mr.  Sweet  as  the  Bad 
River  sandstone.  The  upper  portion  of  the  Potsdam  sand- 
stone, in  this  region  is,  according  to  Rominger,  light-colored 
and  friable,  the  lower  is  dark-red  or  variegated,  and,  as  shown 
by  Mr.  Sweet' s  analyses,  contains  a  large  proportion  of  clay 
and  iron-oxyd,  from  the  decay  of  the  underlying  Keweenian 
strata  (Mem.  Wis(;onsin  Acad.  1876,  page  60). 

^  45G.  The  identity  between  the  crystalline  schists  of  Lake 
Superior  (including  those  of  northern  Michigan  and  Wis- 
consin,) and  those  of  the  Atlantic  belt,  pointed  out  by  the 
write',  in  1870  and  1871,  is  admitted  by  Mr.  Francis  Bradley, 
who,  however,  still  holds,  as  we  have  seen, (§ 404)  to  the  notion 
of  the  i)aleozoic  age  of  the  latter.  In  an  exi)lanation  of 
his  geological  map  of  the  eastern  half  of  the  United  States, 
published  in  1 870,  Mj'.  Bradley  writes :  ' '  The  typical  Iluron- 
ian  of  Canada,  according  to  description,  occupies  the  posi- 
tion, and  presents  the  lithological  characiters  which  we 
should  naturally  expect  for  the  metaniorphic  portion  of  the 
adjoining  Lowev  Silurian  [Cambrian],  corresi>on(ling  pre- 
cisely, in  both  aspe.  ..s,  with  extensive  beds  of  that  age  in 
the  Appalachians.     I  have  accordingly  colored  them  Lower 


IRVING   OX  THE   KOCKS   OF   WISCONSIN. 


E.  235 


Silurian."  "Considerable  portions  of  tlie  so-called  Ar- 
clifcan  area,  in  Wisconsin  and  Michigan,  have  been  shown 
by  Brooks,  Punipelly  and  others,  to  be  the  equivalent  of 
the  Canada  lluronian,  for  which  reason  they  might  with 
propriety  be  referred  to  the  tiilurian,  but  the  data,  as  yet 
published,  seemed  so  incomplete  that  the  writer  has  preferred 
to  leave  them  uncolored."  Bradley  further  remarks,  that 
after  reaching  the  above  conclusion  with  regard  to  the  pale- 
ozoic age  of  the  typical  lluronian:  "I  learned  through 
Mr.  Selwyn,  that  Sir  William  Logan  held  the  same  view, 
for  some  time  before  his  death''  (Amer.  Jour.  Science  III. 
xii,  287). 

To  this  assertion,  Mr.  Selwyn  replies  in  the  same  volume 
(page  4G1),  as  follows:  ''I  am  not  aware  that  I  ever  men- 
tioned Sir  William  Logan  to  Mr.  Bradley,  in  the  matter, 
and  certainly,  if  Sir  William  held  the  views  attributed  to 
him,  he  never  informed  me  of  the  fact."  Mr.  Selwvn  further 
adds,  with  regard  to  the  lluronian  rocks :  ''  AV(^  have  not,  so 
far  as  I  know  at  xjresent,  any  evidence  which  could  warrant 
us  in  classing  them  with  the  Silurian."  To  the  above  decla- 
ration, the  present  writer  must  add  his  owti  testimony  to  the 
effect,  that  Sir  William  Logan,  up  to  the  last  year  of  his  life, 
admitted  no  such  view  as  that  attributed  to  liim  by  Mr. 
Bradley. 

§  4r)7.  The  above  statements  of  Mr.  Bradley  called  forth, 
in  1S77,  a  note  from  Prof.  Irving  (Ibid.  Ill,  xiii,  308),  who 
sums  uj)  as  follows,  "the  facts  i)roven,  thus  far,  as  to  the 
older  rock-series  of  Wisconsin."  These  are,  iirst,  the  exist- 
ence of  an  older  gneissic  and  granitic  series,  the  Laurontian  -, 
second,  the  unconformable  superposition  upon  this  of  a 
second  crystalline  series,  the  lluronian,  (in  which  is  in- 
cluded the  Penokie  giKMssic  foriuatiou  already  mentioned) ; 
third,  the  superposition  upon  the  lluronian,  iu  probabh' 
unconformity,  of  the  great  Keweenian  series,  with  a  thick- 
ness of  several  miles  ;  and  fourth,  the  existence  of  a  seiii's 
of  horizontal  sandstones,  resting  unconformably  upon  the 
Keweenian,  and  liolding  the  organic  forms  of  the  Potsdam 
sandstone. 

Pr(»f.  Irvinir  adds:   "Inoi-der  to  incliid'  the  Wisconsin 


23G  E.      SPECIAL    REPORT.      T.  STERRY  HUNT,  1875. 


crystalline  rocks  witliiii  the  Silurian,  Mr.  Bradley  would 
have  to  stretch  that  term  so  as  to  cover  three  entirely  distinct 
terranes,  each  overlying  its  predecessor  unconformably,  and 
many  thousand  feet  in  thickness  ;  the  highest  of  the  three, 
in  its  turn,  overlaid  unconformably  by  horizontal  sand- 
stones nith  Primordial  [Cambrian]  fossils.  As  to  any  ot 
the  Wisconsin  or  Michigan  rocks  being  altered  equivalents  of 
the  Primordial,  and  newer  strata,  of  the  eastern  States,  such 
a  hypothesis  is  certainly  untenable  for  a  moment."  While 
conceding  that  such  things  may,  as  Bradley  supposed,  oc- 
cur in  the  Appalachians,  (a  region  with  which  Prof.  Irving 
is  unfamiliar)  he  says,  "there  has  certainly  been  no  period 
of  metnmorphism  in  the  region  of  the  northwestern  States, 
since  the  beginning  of  the  Primordial;" — a  proposition 
which  is  equally  true,  in  the  writer's  opinion,  for  the  At- 
lantic belt. 

§  458.  The  Keweenian  series  has  been  shown  to  overlie 
unconformably  the  Iluronian  and  Montalban  schists,  and 
to  be,  in  turn,  overlaid  in  like  manner  by  the  Lower  Cam- 
brian sandstones,  thus  occupying  the  same  geological  in- 
terval as  the  Lower  Taconic  or  true  Taconian  series.  With 
this,  however,  it  has  but  very  remote  lithological  resem- 
I  blances,  and,  so  far  as  known,  nothing  similar  to  the  Ke- 
!  weenian  series  is  found  at  this  horizon,  either  on  this  con- 
!  tinent  or  elsewhere.  If,  however,  as  seems  proba])le  in  the 
present  state  of  our  knowledge,  the  greater  j)ii^i't  of  this 
series  is  to  be  regai-ded,  in  opposition  to  the  opinion  of 
Rivot(§  153)  —  as  of  vokanic  origin,  its  lithological  peculi- 
arities are,  in  the  nature  of  things,  local,  and  have  no 
chronological  signihcance.  We  may  recall,  in  this  connec- 
tion, the  resemblances  already  noticed  between  the  Ke- 
weenian series  and  the  beds  of  amygdaloid  and  cupriferous 
conglomerate,  apparently  of  the  age  of  certain  graptolitic 
shales,  in  the  Upper  Taconic  i-ocks,  in  the  province  of  Que- 
bec (§  185)  and  al.  •  the  similar  rocks  of  mesozoic  age,  in 
other  regions.  Charles  T.  Jackson,  in  1840,  argued  from 
the  litliological  characters  of  the  Keweenian  series,  that  it 
was  of  the  age  of  the  New  Red  sandstone  of  Nova  Scotia, 
Connecticut,  Massachusetts,  and  New  Jersey,  and  the  same 


THE  KEWEEXIAN  SERIES. 


E.  237 


view  has  been  sustained  by-  Ma  r-ou,  and  later,  by  Tliomas 
Macfarlane  and  by  Robert  Bell.  The  valuable  geological 
and  lithological  observations  of  Macfarlane,  in  this  region, 
are  set  forth  in  the  Canadian  Naturalist,  in  1SG8,  (new  series, 
vol.  III.)  where,  on  page  253,  he  has  given  his  reasons  for 
regarding  the  Keweenian  rocks  as  of  the  age  of  the  lloth- 
liegende  or  Permian  of  Germany,  Avhich  they  closely  re- 
semble lithologically. 

§  459.  The  evidence  since  obtained  from  superposition,  has 
however  established  their  much  greater  antiquity,  and  con- 
firms the  opinion,  that  the  comjjosition  of  exotic  rocks  is 
in  no  way  connected  with  the  date  of  their  extravasation. 
The  conditions  under  which  they  have  been  ejected,  whether 
as  sub-aerial,  sub-aqueous,  or  subterranean  eruptions,  and 
the  consequently  differing  conditions  of  consolidatic  i,  must, 
hoAvever,  necessarily  modify  greatly  their  minernlogical 
characters.  It  should  moreover  be  considered,  in  comi)ar- 
ing  older  with  newer  exotic  rocks,  that  the  deeply-seated 
portions  c:''  an  erupted  mass,  which  became  solid  under  a 
vast  pressure,  and  are  now,  in  the  case  of  older  rocks,  ex- 
posed by  great  subsequent  erosion,  must  differ  considerably 
in  structure  from  the  superficial  and  more-rapidly  cooled 
portions  of  the  same  mass.  Of  such  nature,  for  example,  is 
the  difference  between  granites  and  quartziferous  trachytes. 

§  4G0.  There  are  certain  markings  in  the  Keweenian  rocks 
which  are  probably  of  organic  origin.  Logan,  in  1847,  de- 
scribed the  occurrence  in  some  of  the  earthy,  or  so-called 
tufaceous  beds  of  the  series,  of  numerous  slender  vertical 
tubes,  filled  with  calcite,  having  a.  diameter  of  about  a 
quarter  of  an  inch,  and  a  length,  in  some  cases,  of  from  eight 
to  twelve  inches.  Two  or  more  of  these  tubes  were  often 
found  to  coalesce,  in  ascending,  (Geol.  of  Canada,  page  71) 
and  they  were  supposed  by  Logan  to  have  been  formed  by 
currents  of  gas  rising  through  a  pasty  mass.  From  the  ob- 
servations of  the  writer  in  1872,  on  Michii)icoten  Island, 
where  similar  markings  were  found  in  an  argillaceous  stra- 
tum, he  was  led  to  compare  them  with  some  forms  of  so- 
called  ScoliiJius,  and  to  regard  them  as  due  to  the  burrow- 
These  were  accompanied  by  large  niiml)ers 


ing  of  annelids 


m 


2138    E.       SPECIAL    IlEPOllT.      T.  STEUIIY   HUNT,   1875. 

of  two  cuiious  forms,  the  one  club-shaped,  and  the  other 
hemispherical,  or  d<jnie-shaped,  each  recalling  some  sj^onges. 
These,  like  the  tubes,  were  iilled  with  calcite,  agate  or  crys- 
talline quartz,  and  sometimes  in  part  with  a  greenish  chlo- 
ritic  mineral,  ap[)arently  delessite. 

§  461.  The  thickness  of  the  Keweenian  in  the  northeastern 
part  of  Lake  Superior,  as  deduced  from  the  observations  of 
Macfarlane,  is  about  20,000  feet.  The  basal  beds  of  the 
series  are  seen  at  Maniuinse,  and  at  Pointe  aux  Mines,  to 
rest  upon  the  Laurentian  gneiss,  fragments  of  which,  and  of 
Iluronian  greenstones,  were  noticed  by  Macfarlane  in  the 
conglomerates  of  the  series.  These  rocks,  it  is  to  be  ob- 
served, are  what  was  called  by  Logan  the  upper  division  of 
the  Upper  Copper-bearing  series. 

§  462.  The  rocks,  regarded  by  Logan  as  forming  the  lower 
group  or  division  of  the  Upper  Copper-bearing  series,  are 
known  along  the  northwest  shore  of  Lake  Superior,  from 
Pigeon  River  to  Thunder  Bay,  forming  a  belt  on  the  main- 
land, and  also  the  adja(;ent  islands.  The  characters  of 
these  rocks  are  noticed  in  §  137,  and  they  are  described  at 
some  length  in  the  Geology  of  Canada,  pages  67-70.  A 
further  account  of  these,  with  some  analyses,  was  given  by 
Macfarlane  in  1869,  in  a  paper  on  the  Geology  of  Wood's 
Location,  (which  includes  Silver  Islet,)  (Can.  Naturalist,  new 
series,  IV,  pages  37-48  and  459-463).  The  dark  bluish- 
gray  slates  were  found  to  owe  their  color  to  carbonaceous 
matter,  and  the  impure  limestones  of  the  series  were  dolo- 
mitic.  The  carbonaceous  nature  of  this  formation  is  further 
shown  by  the  presence  of  an  anthracitic  substance,  both 
disseminated,  and  tilling  small  iissures  in  certiiin  chalcedonic 
and  flinty  layers.  (Geol.  of  Canada,  page  68.)  This  series 
of  nearl}^  horizontal  strata  is  traversed  by  dykes  of  dioritic 
rocks,  which  have  been  studied  by  Macfarlane,  and  both  of 
these,  in  their  turn,  are  cut  by  veins  carrying  native  silver 
and  various  ores,  in  a  gangue  of  quartz  and  calcite. 

§  463.  The  overlying  rocks,  according  to  the  descriptions 
of  Macfarlane,  and  the  later  observations  of  Prof.  Roliert 
Bell,  given  in  the  report  of  the  Geological  Survey  for  1866- 
69,  page  319,  consist  of  red  and  white  dolomitic  sandstones 


THE  ANIMIKIE  AND  NIPIGOX  GUOUPS. 


E.  289 


and  shales,  with  interstratified  reddish  limestones,  and 
variegated,  yellow,  red  and  greenish  doloniitic  marls,  from 
which  issue  brine  springs.  This  second  group,  as  seen  to 
the  west  of  Black  Bay,  overlying  the  lower  group  of  dark- 
colored  carbonaceous  strata,  dips  gently  to  the  eastward, 
and  has  a  thickness  of  1370  feet.  On  the  east  side  of  Black 
Bay,  appears  a  great  series,  estimated  at  from  six  to  ten 
thousand  feet  in  thickness,  of  sandstones  and  conglomerates, 
interstratified  with  trappean  rocks,  often  amygdaloidal. 
Above  all  this,  is  a  vast  overflow  of  columnar  doled  tic  rock, 
which,  according  to  Bell,  rests  unconformably  upon  the 
various  groups  already  described,  including  I,  the  lower 
dark-colored  carbonaceous  strata ;  II,  the  succeeding  red  and 
variegated  sands<tones,  limestones  and  marls ;  and  III,  the 
conglomerates  and  amygdaloids.  These  three  groups  were, 
by  Bell,  supposed  to  form  parts  of  the  so-called  Upper  Cop- 
per-bearing series,  whi<!h  he,  from  the  combined  litliological 
resemblances,  compared  with  "the  rocks  of  Permian  or  Tri- 
assic  age  in  Nova  Scotia"  (page  321).  To  this  suggestion. 
Sir  W.  Logan  replied  in  the  same  volume,  (pages  472-475), 
pointing  out  the  reasons  for  placing  below  the  St.  Mary's 
sandstone,  the  copper-bearing  conglomerate  and  amygdaloids 
of  the  two  sides  of  Lake  Superior,  of  which  group  III,  men- 
tioned above,  is  supposed  to  form  part. 

§  4G4.  The  strata-  of  groups  I  and  II  Avere,  by  Logan,  as  by 
Bell,  regarded  as  the  lower  members  of  one  great  conforma- 
blt  series,  of  which  the  amygdaloids  and  conglomerates 
form  the  upper  part,  but  the  writer,  in  1872,  found  on  the 
main  land,  not  far  from  Silver  Islet,  in  a  conglomerate  which 
forms  the  base  of  group  II,  pc^bbles  clearly  dei'ivcd  from 
the  lower  group.  The  latter,  which  presents  at  Thunder 
Cape  a  vertical  section  of  1300  feet  of  horizontal  strata,  is, 
moreover,  entirely  wanting  a  few  miles  to  the  eastward,  in 
Black  Bay,  where,  according  to  Logan,  the  red  sandstones 
of  II  rest  upon  the  Laurentian  ;  a  fact  which  suggests  a  want 
of  conformity  between  the  two  sandstone  groups. 

§  40o.  These  relations  were  lirst  descrilxvl  by  the  writer, 
in  his  address  on  the  (leognostical  Relations  of  (lie  Metals, 
given  before  the  American  Institute  of  Mining  Engineers,  in 


240  E.      SPECIAL   REPOIIT.      T.  STERRY   HUNT,  1875. 


((, 


February,  1873,  when  the  older  group  was  noticed  as  '"a 
series  of  dark-colored  argillites  and  sandstones,  which  are 
as  yet  known  only  in  this  region,  and  are  overlaid  in  slight 
discordance  by  red  and  white  sandstones,  apparently  the 
same  with  those  of  the  Keweenaw  district,  and  the  St. 
Mary's  Ri-ver.  This  older  series,  of  Thunder  Bay  and  its 
vicinity,  which  may  be  named  the  Animikie  series,  from  the 
Indian  name  of  the  bay,  is  the  lower  division  of  the  Upper 
Copper-bearing  series  of  Logan.  The  great  Keweenian 
group,  with  its  cupriferous  amygdaloids,  is  here  absent, 
though  met  with  a  few  miles  furthcn*  to  tlie  eastward." 
(Trans.  Amer.  Inst.  Mining  Engineers,  I.  339.) 

§  46G.  In  his  exploratit)ns,  in  1872,  Prof.  Bell  found  the 
nearly  horizontal  slates,  sandstones  and  marls  of  group  II, 
(whether  with  or  without  I,  is  not  clearly  stated)  with  the  in- 
tersecting and  overlying  columnar  trap,  largely  developed 
around  Lake  Nipigon,  to  the  north  of  Lake  Superior,  and 
suggested  for  the  whole  Upper  C()pi)er-bearing  series,  (in 
wiiicli  he  included  these  horizontal  strata)  the  name  of  the 
Nipigon  group.  (Report  for  1872-73,  page  100).  In  a 
further  communication  on  the  rocks  of  this  region  to  the 
Institute  of  Mining  Engineers,  in  May,  1873,  the  writer  pro- 
posed to  adoi^t  this  name  of  Nix)igon  for  the  red  sandstones 
and  nuirls  of  II,  while  retaining  the  name  of  Animikie  for 
the  lower  group,  I.     (Trans.,  etc.,  II,  59). 

§  407.  In  the  view  of  Logan,  the  Upper  Copper- bearing 
series  consisted,  in  ascending  order,  of  I,  the  Animikie  group  ; 
IT,  the  Nipigon  group,  as  above  restricted,  (neither  of 
these  being  cupriferous),  and  III,  the  overlying  cupriferous 
conglomerates  and  trappean  rocks  which  we  have  named 
the  Keweenian  series.  Macfarlane,  on  the  other  hand,  re- 
garded the  Nipigon  group  as  the  equivalent  of  the  horizon- 
tal sandstones  which,  elsewhere  in  the  lake,  overlie  the  Ke- 
weenian series.  lie  had  moreover  previously  noticed  a 
series  of  bluish  sandstones  and  slates,  very  unlike  the  red 
St.  Mary's  sandstones,  overlying  unconformably  the  basal 
beds  of  the  Keweenian,  where  these  rest  upon  the  Lauren- 
tian,  near  Pointe  aux  Mines  ;  and  subsequently  pointed 
out  the  close  correspondence  in  structure,  and  in  general 


LIST  OF  PRE-SILURIAN  TEHUANES, 


E.    241 


lithological  cliaracters,  between  tliese  bluish  overlying 
sandstones,  and  the  lower  or  Animikie  group  oi  Thunder 
Bay.     (Canadian  Naturalist,  new  series,  III,  252;  IV,  38). 

§  468.  In  accordance  with  these  facts,  the  Animikie  and 
Nipigon  groups  are,  by  the  writer,  regarded  as  belonging 
to  two  distinct  series,  both  younger  than  the  Keweenian. 
The  lithological  characters  of  the  Nipigon  group  are,  more- 
over, very  distinct  from  the  Cambrian  sandstones  found  at 
Saidt  Ste.  Marie,  and  along  the  southern  shore  of  Lake 
Superior,  with  which  it  was  formerly  confounded,  and  it 
will  probably  be  found  to  belong  to  a  more  recent  period; 
so  that  while  the  Keweenian  series  is  preCambrian,  the 
Nipigon,  and  also  the  Animikie  group,  may  be  post-Cam- 
brian, and  perhaps  mesozoic. 

§409.  The  results  of  our  studies  of  rhe  older  rocks  of 
eastern  North  America,  including  the  Lake  Superior  region, 
show  the  existence  of  the  following  series,  constituting  as 
many  distinct  terranes,  the  stratigraphical  relations  between 
which  have  already  been  pointed  out  (§  416).  These 
terranes  are,  in  ascending  order,  as  follows  : 

I.  Laurentian  ; — consisting  of  a  lower  division,  tlio  Ottawa 
gneiss,  andiin  upper  division,  tlieOrenvillo  series,  between 
wliicli  is  a  supposed  want  of  conformity.  Tiiese  two,  to- 
gether, constitute  the  Lower  Laurentian  of  Logan. 

II.  NouiAN  : — the  Labradorian,  or  Upper  Laurentian  of  Logan. 

III.  IIukonian; — the  Green  Mountain  series,  or  Altered  Quebec 

group  of  Logan. 

IV.  MoNTALBAN ; — the  White  Mountain,  or  Mica-Schist  series. 

V.  Taconian  ; — the  Lower  Taconio  of  Emmons,  or  tliolliistings 
series,  including  a  part  of  the  Primal,  Auroral,  and  Mati- 
nal  divisionsof  Rogers;  and  constituting,  witli  theMontal- 
ban,  what  was  once  called  Terranovan  by  the  writer. 

VI.  Keweenian  ; — the  Copper-bearing  series  of  Lake  Superior, 
I'oimd  in  the  same  geological  interval  ua  the  Taconiau,  but 
not  idontilit'd  with  it. 


VII.  Camhkian;— tlio  Lower  and  Middle  Cambrian  of  Sedgwick, 
and  tlie  Lower  and  Upper  Cambrian  of  Hicks;  being  the 
Upper  Taconic  of  Emmons,  and  the  Quebec  group  of  Lo- 
gan ;  or  the  Primordial  Silurian,  and  part  of  the  Lower 
Silurian,  of  Murchisou. 

[16  E.] 


p, 


242  E.      SPECIAL  REPORT.      T.  STERRY  HUNT,  1875. 

VIII.  Siluuo-Cambbian  :— the  Upper  Cainbriun  of  Sedgwick  ; — 
part  oCiho  Lower  Silurian  of  Muroliisoii.  and  tlio  Matinal 
of  Rogers,  in  part. 

§  470.  The  Cambrian  sediments  present,  in  the  regions 
here  considered,  notable  variations  in  vohime  and  lithological 
characters,  depending  upon  the  sources  from  which  they 
were  derived.  The  Cambrian  sandstones  and  dolomites  of 
the  Mississippi  valley,  and  of  the  Ottawa  basin,  formed  in 
I)roximity  to  areas  of  quartzo-feldspathic  gneisses  and  petro- 
silexes,  are  very  unlike  their  stratigraphical  equivalents, 
the  Upper  Taconic  or  Quebec  group,  derived  in  large  part 
from  the  ruins  of  the  Huronian  and  Montalban  schists, 
which  formed  the  eastern  shores  of  the  Cambrian  ocean. 
Those  who  have  imagined  these  crystalline  rocks  to  be  the 
altered  equivalents  of  the  Cambrian  sediments  found  along 
their  northern  and  westein  borders,  having  unwittingly  ex- 
cluded the  only  reasonable  explanation  of  the  lithological 
peculiarities  of  these  sediments.     (§  229  and  §  404.) 

471.  "The  distribution  of  the  crystalline  rocks  of  the 
Norian,  Huronian  and  Montalban  series,  suggests  the  view 
that  these  are  remaining  portions  of  great,  distinct  and 
unconformable  series,  once  widely  spread  over  a  more 
ancient  floor  of  granitic  gneiss  of  Laurentian  age ;  but 
that  the  four  series  mentioned  incluT  the  whole  of  the 
stratified  formations  of  eastern  North  America,  is  by  no 
means  certain.  IIow  manv  formations  may  have  been  laid 
tlown  over  this  region,  and  siibseqiumtly  swept  away,  leav- 
ing only  isolated  fragments,  we  may  never  know ;  but  it  is 
probable  that  a  careful  study  of  the  geology  of  New  Eng- 
land, and  the  adjacent  ]3i'itisli  provinces,  may  establish  the 
existence  of  many  more  than  the  four  series  above  enumera- 
ted." (Compare  Trans.  Amer.  Inst.  Mining  Eng.  I,  383,  with 
Chem.  and  Geol.  Essays,  page  281).  The  importance  of  the 
Taconian,  as  a  fifth  series  of  crystalline  rocks,  distinct  from 
the  Montalban,  was  not  at  that  time  (1873)  recognized  by  the 
author.  It  is  not  impossible  that  some  of  the  sub-divisions 
of  eozoic  rocks  described  by  Prof.  C.  H.  Hitchcock,  in  his 
recently  published  Geology  of  New  Hampshire,  may  be  en- 
titled to  the  rank  of  distinct  series.     A  discussion  of  the 


LAUBENTIAN  OF  THE  llOCKY  MOUNTAINS.         E.  243 


m 


questions  which  arise  in  this  connection  would  however  re- 
quire a  space  beyond  the  limits  of  the  present  liistory.  (See, 
in  this  connection,  Chem.  and  Geol.  Essays,  page  282.) 

A  similar  remark  must  apply  to  the  many  valuable  obser- 
vations and  generalizations  made  by  Mr.  W.  O.  Crosby,  in 
his  report  on  the  Geological  Map  of  Massachusetts,  being 
a  map  sent  l)y  the  Boston  Society  of  Natural  History  to 
the  Cent(Minial  Exhibition,  in  1870.  Mr.  Crosby's  report, 
and  the  added  remarks  of  Prof.  L.  S.  Burbank,  are  impor- 
tant contributions  to  the  geology  of  eastern  New  England, 
and,  like  the  more  extended  studies  of  Prof.  Hitchcock,  are, 
with  some  minor  exceptions,  in  full  accordance  with  the 
views  already  set  forth  by  the  writer  in  the  preceding  pages. 

§  472.  The  application  of  these  distinctions,  made  in  the 
east,  to  the  crystalline  rocks  of  the  western  part  of  the  con- 
tinent, is  a  task  which  is  only  begun.  The  late  Mr.  Mar- 
vine,  in  Ilay den's  report  of  geological  explorations  for  1873, 
compared  the  gneissic  rocks  of  the  Rocky  ^fountains,  in 
Colorado,  to  the  Laurentian.  The  writer,  in  a  communica- 
tion to  the  American  Association  for  the  Advancement  of 
Science,  in  August  1877,  confirmed  this  conclusion  of  Mar- 
vine's  from  his  own  observations  near  Fort  Garland  in  the 
Sangre  de  Cristo  range,  and  also  in  Glen  Eyrie,  in  the  Ute 
Pass,  in  Clear  Creek  Canion,  and  about  Georgetown,  in 
Colorado.  "  In  all  of  the  localities  he  found  gneisses,  often 
hornblendic,  but  scarcely  micaceous,  and  in  many  cases  in 
large  masses,  often  granitic  in  aspect,  with  rarely  inter- 
bedded  gneissic  layers.  These  strata  are  penetrated,  in  the 
neighborhood  of  Georgetown,  by  well-niurked  granilic 
masses,  probably  exotic.  The  red  granitoid  rocks,  at  and 
near  Sherman,  on  the  Union  Pacific  Railroad,  are  probably 
gneissic.  These  various  rocks  have  all  the  lithological 
characters  of  the  Laurentian,  as  disijlayed  in  the  Laurentides, 
the  Adirondacks,  and  the  South  Mountain  between  the 
Hudson  and  Schuylkill  Rivers.''  ''The  gneissic  rocks  of 
the  Wahsatch  range,  as  seen  in  the  Devil's  Gate  on  the 
Weber  River,  are  also  Laurentian,  to  which  are  to  be  re- 
feiTed  the  simila  'ratified  rocks  found  in  the  same  range, 
further  south,   in  ue  upper  part  of   Little  Cottonwood 


244  E.     si'i;(  lAL  itin-om.     t.  stkkuy  hunt,  1875. 


Canion.  Here,  amon^  loose  blocks  of  the  gneiss,  were 
I'ourul  occasional  masses  of  coarsely  ciystallint;  limestone, 
with  niicn,  and  also  varieties  ol"  pyroxenif^  rocks,  character- 
isti<;  of  the  Ijaiirentiun.  At  the  lower  part  of  the  sjime 
canion,  there  are,  however,  well-marked  erui)tivegi'anites." 

$5  475}.  "The  crystalline  schists  examined  by  the  writer 
in  the  foot-hills,  at  the  western  l)aseof  tlu^  Si«'rras,  in  Ama- 
dor, Phurr,  and  Nevada  conntit^s,  in  (blifornia,  have, 
according-  to  him,  :ill  the  characiters  of  the  Ilnronian  series, 
as  seen  on  the  iireiit  lakes  in  eastein  Noi'th  America,,  and  in 
the  Alps.  The  aniiferons  (piaitz-veins,  in  the  connties 
above  named,  are  fonnd  traversing-  alike  the  crystalline 
schists,  and  the  <ii'anltes  of  the  rej-ion,  which  are  probal)ly 
ernptive  nuisses  newer  than  the  schists.  To  the  Ilunmian, 
he  also  refers  the  similar  crystalline  rocks  of  tlie  Coast 
ran,i;'e  of  Calil'oi'nia,  as  seen  near  San  Franc.'isco,  and  near 
San  Jose."  (^Proc.  Amer.  Asso<'.,  1877,  and  also  Proc. 
Bost.  Soc.  Nat:  Hist.  XIX.  27(5).  Reference  has  already 
been  made  to  the  probable  existence  of  Norian  rocks  in 
Wyoming,  on  the  Laramie  Plains  (§  315). 

Since  the  pid)lication  of  tlie  above  observaticms,  the 
second  volnme  of  Mr.  Clarence  King's  Survey  of  the  Fortieth 
Parallel  has  a|)peared,  in  which  Mr.  S.  F.  Emmons  supports 
the  view  of  tlie  Lanrentian  age  of  the  gneisses  of  the  Colo- 
I'ado  range.  Various  observations  in  his  report  make  it 
prt)l)able  that  other  and  newer  eozoi(?  terranes  are  repre- 
sented in  the  vast  Primary  areas  lying  between  this  range 
and  the  Nevada  basin. 

§  474.  Allusion  has  been  made  above  to  the  Huronian  of 
the  Alps,  to  which  period  Gastaldi  lias  referred  the  great 
series  of  rocks,  there  known  as  the  pletrl  verdi^  or  green- 
stones. These  consist  of  dioritic  and  feldspathic  rocks, 
(including  the  gabln-os  and  euphotides),  with  seri)entines, 
steatites,  and  chloritic,  epidotic  and  quartzose  schists,  smd 
have  been  regarded  by  most  geologists  as,  in  part,  erui^tive, 
and,  in  part,  so-called  contact-deposits,  resulting  from  the 
action  of  erupted  masses  upon  uncrystalline  sedimentaiy 
strata.  Such  a  hypothesis  was,  as  we  have  seen,  held  by 
II.  D.  Rogers  with  regard  to  the  similar  rocks  in  Penn- 


lot" 
(at 
lil- 
ts, 


1(1 

le 

y 

i>y 
1- 


\ 


IIUROiNIAX  AND  LAUKKXTIAN  OF  THE  ALPS.      E.    245  ^ 

sylvania,  and  has  lar»'ly  been  resuscitated  for  them,  in  New-  v^ 

foiiudlaud,  (^  :}77-379).     Nicholson,  moreover,  a  few  yearn  .  >\  v 
since,  applied  a  like  view  to  the  Ilnronian  of  Lake  Superior,  c^v    /  •  , 
and  recently  George  }>[.  Dawson  has  expressed  the  opinion     \^    /  ri'\ 
that  rocks  litholoirically  similar  to  these,  in  liritish  Colum-H^s'^y^'f*'  ^ 
bia,  are  of  volcani<'  oiii;in,  and  niesozoic  in  age. 

^474.  The  greenstone  gronp  of  the  Alps  has,  like  tin? 
similar  rocks  in  North  America,  been,  from  its  apparent 
stratigraphlcal  relations  in  dillVivnt  localities,  assigned  to 
various  ages,  in  paleozoic,  mesozoic,  and  cenozoic  time. 
The  late  researches  in  Alpine  geology,  of  Favre,  Gastaldi, 
and  others,  have  howv'ver  led  to  a  different  c(mclnsion. 
According  to  the  latter,  the  rocks  of  the  greenstone  groujj 
are  not  eruptive,  but  indigenous,  and  constitute  a  dis- 
tinct stratilled  series,  of  great  thickness,  of  beds  and  len- 
ticular masses,  in  which  the  serpentines  occupy  a  position 
near  the  base.  These  vai'ious  rocks,  he  declares,  belong 
to  a  constant  and  well-defined  horizon,  which  is  pre-paleo- 
zoic,  and  never  make  theii-  appeanince  in  other  formations. 
This  group  has  all  the  characters  of  the  Ilnronian  or  Green- 
Mountain  series,  to  which  it  has  lieen  refei-red  by  (iastaldi, 
and  rests,  probably  unconformably,  upon  a  great  series  of 
gneissic  rocks,  often  porijhyroid  and  granitoid,  which  in- 
clude quartzites,  graphite,  and  crystalline  limestones,  and 
are  supposed  by  him  to  represent  the  Laun^ntian,  of  which 
they  have  the  chai-acteristics. 

§47,").  The  Iluronian  in  northern  Italy  is  followed  by  a 
great  series  of  quartzites,  with  calcareous  schists,  mica- 
ceous limestones,  and  dolomites,  including  gypsums  near 
the  summit.  These  rocks,  like  the  pieiri  verdi,  have  been, 
in  turn,  referred  to  various  horizons  from  the  Cretaceous  to 
Lower  Carboniferous,  but  a(;cording  to  Gastaldi,  are  of 
greater  and  uncertain  antiquity.  Their  lithological  char- 
acters, and  their  position,  recall  the  Taconian  of  eastern 
North  America.  The  three  groups  of  crystalline  strata 
above  mentioned,  are  said  by  Gastaldi  to  constitute  the  basal 
rocks  of  Alps  and  the  Appenines,  and,  overlaid  in  part  by 
newer  strata,  may  be  followed  fi-om  Mont  Blanc  to  the  Dan- 
ube, the  Adriatic,  the  Mediterranean,  and  the  plains  of 


246  E.      SPECIAL   KEPOUT.      T.  STERRY   HUNT,  1875. 


Fiunce.     Gneisses  and  mica-schists,  similar  to  those  oi"  the 
Montalban  series,  are  also  found  in  many  parts  of  rhe  Alps. 

The  '•ead'>r  may  consult  on  this  subject,  two  remarkable 
memoirs  by  Gastaldi,  entitled,  Sludli  Oeologice  sulle  Alpi 
Occkic'/dall,  and  the  same,  parte  scconda  ;  Firenzo,  1871  and 
1874,  in  quarto,  with  numerous  maps  and  sections ;  also 
a  letter  by  this  geologist,  entitled  Spaccata  Geolofftee  liimjo 
le  ValU  Super iori  del  Po^  etc.,  {BoUetino  del  II.  Comltato 
Oeologico,  unno  187G,  No.  3^).  See  further,  Bui.  Sac. 
Ghl.  de  France,  3me.  s^rie.  I,  208,  and  on  The  Geology 
of  the  Alps,  Chem.  and  Geol.  Essays,  i)ages  329-348.  The 
views  of  Favre  and  Gastaldi,  though  still  opposed  l)y  some 
of  the  older  school  of  geologists,  are  in  harmony  with  all 
the  facts  of  American  geology,  as  set  fortli  in  the  preceding- 
pages. 

§  470.  For  a  study  of  the  euphotides  and  gabbros  of  the 
Alps,  in  vvhich  the  saussurite  of  the  typical  eupliotide  is 
shown  to  be  not  feldsjiathic,  but  epidotic ;  and  for  an  ex- 
tended comparison  of  these  rocks  with  the  relatt.'d  ones  of 
the  Iluroiiian  of  the  Atlantic  belt,  see  the  author's  memoir 
on  Eupliotide  and  Saussurite,  (Amer.  Journal  Science,  II, 
xxvii.,  330).  For  a  similar  study  of  serpentines,  see  his 
Contributions  to  the  History  of  Ophiolltes,  (Ibid,  II,  xxv, 
217,  and  xxvi.  234). 

§  477.  Some  further  account  of  the  Montalban  rocks,  and 
their  inchided  granitic  veinstones,  may  be  found  in  th<' 
author's  Chemical  and  Geological  Essays,  pages  194-200. 
The  relations  there  pointed  out,  on  pages  192  and  208,  be- 
tween granitic,  calcareous  and  metalliferous  quart/  vein- 
stones, are  well  shov^  in  Northbridge,  near  Worcester, 
Massac^husotts,  where  the  gray  fine-grained  gneisses  of  the 
Montalban  series,  dipping  to  the  soutlieast,  are  travf^rsed 
at  right  angles  by  several  vertical  ])arallel  veins,  which  may 
be  traced  for  considerable  distances,  and  are  ordiiiarilv  but 
a  few  inciies  in  thickness.  The  veinstone  in  these  is  gener- 
ally a  vitreous  quartz,  which  in  sr)me  parts  exhibits  sel- 
vages, and  in  others,  bands  of  white  orthoclase,  by  an  ad- 
mixture of  whicli  it  elsewhere  passes  into  a  well  characterized 
granitic  vein.    Tlie  ipiartz  veins,  in  phices,  hold  cubic  crys- 


THICKNESS  OF  THE  HURONIAN  SERIES, 


E.  247 


tals  of  pyrite,  together  with  clialcopyrite  and  pyrrliotine, 
the  latter  in  considerable  masses,  sometimes  accompanied 
by  crystals  of  greenish  epidote,  embedded  in  the  quartz, 
and  occasionally  associated  with  red  garnet.  In  one  part, 
tliere  is  found  enclosed  in  the  wider  part  of  a  vein,  between 
walls  of  vitreous  quartz,  a  lenticular  mass,  three  inches 
thick,  of  coarsely  cleavable  pink  calcite,  with  imbedded 
grains  of  dark  green  amphibole,  and,  on  one  side,  small 
crystals  of  olive-green  epidote  and  red  garnet ;  the  whole 
mass  closely  resembling  some  crystalline  limestones  from 
the  Laurentlan. 

§478.  In  the  account  previously  given  of  the  Iluronian 
and  Montalban  rocks,  as  observed  by  Brooks  to  the  south 
of  Lake  Superior,  a  notice  of  his  latest  publication  on  the 
subjei  t,  which  appeared  in  September,  187G,  (Amer.  Jour. 
Sviience  III,  xii,  jiage  194, )  was  inadvertently  omitted.  In 
the  tabular  view  there  printed,  the  crystalline  rocks,  by 
Brooks  called  Iluronian,  are  divided  into  twenty  groups. 
The  granitoid  gneisses,  already  referred  to,  (^  4:}G-4;}8)  as 
associated  with  the  "great  hornblendic  and  mica-schist 
series,"  XIX,  previously  regarded  as  forming  the  summit 
of  the  system,  are  now  described  as  still  newer  than  this, 
and  are  spoken  of  as  "the  youngest  observed  member,  the 
granitic  bed,  XX, — only  recently  made  out."  It  is  these 
two  divisions,  XIX  and  XX,  which  the  wi-iter  has  already 
referred  to  the  Montalban,  and  which,  according  to  Brooks, 
0(Hui])y  large  areas  both  in  the  Menomenee  and  the  Penokie 


regions. 


§  479.  The  observed  thickness  of  the  Iluronian  in  this 
region,  exclusive  of  the  overlying  gneissic  series,  is  esti- 
nuited  by  Brooks  at  not  over  GOOO  feet  for  the  Marquette 
district,  and  for  those  lying  further  west,  on  Black  River,  in 
Michigan,  and  where  the  Bad  River  crosses  the  Penoki«> 
I'ange,  in  Wisconsin.  To  the  south  of  Marcpiette,  in  the 
J.Ienomenee  district,  it  is  said,  the  exposures  may  exceed 
12,000  feet.  We  have  however  seen  that  in  Wisconsin, 
according  to  Irving,  the  quartzites  alone,  of  the  Iluronian, 
in  one  section,  measure  over  4000  feet,  and  the  petrosilex- 
porphyries.  in  another,  not  less  than  3200  feet  (§  451).     If 


248  E.      SPECIAL   REPOET,      T.  STERRY  HUNT,  1875. 


these  rocks  be  comprehended,  the  estimates  of  18,000  and 
20,000  feet  of  aggregate  thickness,  made  by  Murray,  and  by 
Credner,  (§  430)  do  not  seem  excessive.  Although  the 
petrosilcxes  were  not  noticed  by  the  former,  tlie  presence; 
of  them,  lately  detectetl  by  the  writer  in  the  collections 
made  by  Murray,  twenty  years  since  on  Lake  Huron,  show 
that  these  rocks  were,  by  that  observer,  probably  included 
under  the  head  of  cherts  and  jasi)ers. 

The  Iluronian  series  in  New  Hampshire,  excluding  the 
petrosilex-porphyries,  called  by  him  Lower  Huronian, 
(§371)  is,  according  to  C.  H.  Hitchcock,  a  little  over  12,000 
feet  in  thickness. 

§  48(>.  The  thickness  of  the  Montalban,  as  seen  through- 
out the  Atlantic  belt,  appears  to  be  very  greii  t.  Hitchcock, 
in  his  Geology  of  New  ILimpshire,  jiublished  in  1877,  (Vol. 
II,  page  074)  includes  under  this  name  a  series  described  as 
gneisses  and  feldspathic  mica-schists,  librolite-schists,  and 
"Concord  granites," — the  local  designation  of  the  fine- 
grained grayish  micaceous  gneisses  of  the  Montalban.  This 
series  has,  according  to  him,  an  aggregate  thickness  of 
11,370  feet.  Beneath  this, he  places  34,900  feet  of  rocks  desig- 
nated as  Laurentian,  of  which  however  the  upper  portion, 
called  the  Lake  gneiss,  and  estimated  at  18,000  feet,  is 
in  the  writers  opinion,  probably,  Montalban.  Notwith- 
standing the  a]iparent  absence  of  the  Huronian  beneath  the 
Montalban  in  I  he  sections  given  l)y  Hitchcock,  the  writer 
has  already  set  forth  his  reasons  for  believing  the  latter  to 
be  the  younger  series.  It  is  probable  that  a  portion  of  the 
crystalline  scliists  which,  in  certain  sections,  overlie,  ac- 
cording to  Hitchcock,  the  Huronian,  may  also  belong  to 
the  Montalbjui  terrane. 

§  481.  As  we  have  already  seen,  the  hypothesis  put  for- 
ward by  Matlier,  n  1843,  that  the  whole  of  the  crystalline 
rocks  of  western  New  England  are  but  altered  paleozoic 
strata  of  th(^  Cliamplain  division,  (^81)  has  lately  been  re- 
vived by  Prof.  Bradley,  who  has  extended  it  to  the  similar 
rocks  of  the  Blue  Bidge,  and  of  the  vicinity  of  Lake  Su- 
perior (§404,  456).  In  a  Handbook  of  Georgia,  published 
by   the  Commissioner  of  Agriculture  for  tliat  State,  in 


THE    BLUE   RIDGE   IN    GEORGIA. 


E249 


1876,  and  accompanied  by  a  geological  map,  is  a  sketch  of 
the  geology  of  Georgia,  which  is  understood  to  embody  the 
opinions  of  Bradley  with  regard  to  the  crystalline  rocks 
of  that  State. 

It  is  therein  declared  that  Fulton  county  exhibits  both 
"the  Cincinnati  gneisses,"  and  "the  reddish  and  gray  hydro- 
mica  schists,  with  some  outcrops  of  the  steatite  and  itacol- 
undte,  of  Quebec  age."  In  Habersham  county,  the  rocks 
are  referred  to  the  same  two  divisicms  ;  those  of  the  Blue 
Ridge  jH'oper,  like  those  of  the  Chattahoochee  Ridge,  being- 
said  to  consist  of  "hard  horublendic  gneiss  of  Cincinnati 
age,"  while  the  softer  schists  of  (he  intermediate  valleys 
are  supposed  to  belong  to  t'  Quebec  period,  (loc.  cit., 
pages  40,  49,  59.) 

§  482.  These  same  views  are  set  forth,  with  further  detail, 
in  the  exi)lanations  accompanying  the  catalogue  of  a  col- 
lection of  the  rocks  and  minerals  of  Geoi-gia,  sent  to  the 
Paris  exhibition  of  1878 ;  the  catalogue  having  been  prepared 
by  Dr.  George  Little,  the  State  geologist.  It  is  theicin  said 
of  the  crystalline  rocks  of  the  State,  that,  altiiough  without 
fossils,  they  "apx)arently  are  all  stratigraphical  ecpiivalents 
of  the  Lower  Silurian  :  "in  which  however  the  only  divisions 
recognized  are  the  following,  in  ascending  order  :  1 .  Acadian 
or  Lower  Potsdam  ;  2.  Upper  Potsdam  ;  3.  Quebec  grouj), 
and  4.  Cincinnati  group.  The  thicknesses  there  severally 
assigned  to  tliese  are  given  vvitli  a  qu(My. 

The  first,  or  Acadian,  estimated  at  13,000  feet,  is  said  to 
consist  of  micaceous  and  livdro-micaceous  schists,  witli 
bands  of  gneiss,  having  but  little  hornbh:'nde.  It  also  in- 
cludes rooiing-slates.  The  second,  or  Upper  Potsdain,  of 
2,000  feet,  is  made  up  of  heavy-l)edded  gneisses,  with  little 
hornblende,  as  before,  and  with  few  schists.  The  thiid,  or 
Quebec  group.  12.000  feet  thick,  consists,  in  its  lower  ])ai't, 
chiefly  of  hydro-mica  schists,  with  Ix^dsof  honiblende-schist, 
gneiss,  and  quartzite,  with  much  gai'Utit,  cyaniteaiid  rutile  ; 
and  in  its  upper  i)art  includes  limestone  and  dolomites,  with 
beds  of  chrysolite-rock  or  dunite,  associated  with  serpentine 
and  other  niagnesian  ndnerals,  and  with  corundum.  The 
fourth,  or  Cincinnati  group,  15,000  feet  thick,  is  chiefly 


2oO  E.      SPECIAL   REPORT.      T.  STERRY   HUNT,  1875. 


gneiss,  in  great  part  hornblendic,  with  but  few  liydro-mica 
Rchists,  "It  probably  includes  the  flexible  sandstones  of 
the  npper  part  of  the  Itacolumite  series  of  Lieber,"  the 
lower  part  of  whic^h  is  said  to  be  embraced  in  the  Quebec 
group.  All  of  these  divisions  are  declared  to  be  more  or 
less  auriferous,  with  the  exception  of  the  Acadian  ;  bat  the 
rocks  holding  the  chief  part  of  the  gold  of  the  region  are 
placed  in  the  lower  portion  of  the  Quebec  group. 

§  483.  The  vvuiter  has  very  recently  had  the  advantage  of 
examininti:,  in  some  detail,  the  crystalline  rocks  of  the  region 
in  qnestion,  in  company  with  Br.  Little.  The  roc^ks  of  the  so- 
called  Cincinnati  group,  whether  seen  in  the  vicinity  of 
Atlanta,  Fulton  county,  at  Mount  Airy,  Habersham  county, 
or  at  various  p'^ints  intermediate,  along  the  line  of  the  con- 
necting railway,  are  the  characteristic  hornblendic;  gneisses 
and  mica-schists  of  the  Montalban.  The  same  is  true  of  the 
greater  part  of  the  rocks  exposed  in  the  se('tionfrom  Mount 
Airy,  by  the  base  of  INlount  Yonah,  to  the  Unaka  Gap  in  the 
Blue  liidge,  in  AVhite  county  ;  nor  was  there  met  with  in  this 
section  across  the  whole  mountain-belt  anything  represent- 
ing the  Iluronian,  or  so-called  altered  Quebec  group;  as  seen 
in  the  Green-Mountain  range  in  Canada.  In  the  valley  on 
the  northwest  of  the  Chattahoochee  Ridge,  near  Clarksville, 
in  Habersham  county,  there  were  found  outcrops  of  unctuous 
slates,  which  resemble  those  of  the  Taconian,  and  mav  be 
associated  with  the  limestones,  said  by  Prof.  Bradley,  to  be 
quarried  in  the  vicinity.  The  whole  section,  including  the 
gold-bearing  strata  of  the  Nacoochee  valley,  bears  a  close 
resemblance  to  that  already  described  across  the  same 
mountain-belt  to  the  southeast  of  Roan  Mountain,  in  North 
Carolina  (§  207.)  Stcme  Mountain,  near  Atlanta,  ic  a  good 
example  of  the  micaceoi  s  granitoid  gneiss  of  the  Montalban, 
so  well  known  in  New  England  ; — the  Concord  granite  of 
Hitchcock. 

§  484.  The  Montalban  rocks  throughout  this  region  are, 
with  local  exceptions,  (as  in  the  mountain  just  named,) 
more  or  less  completely  decayed,  often  to  a  depth  of  lifty 
feet.  The  liornblendic  gneisses,  though  still  retaining  con  ■ 
sidei-able  coherence,   have  lost  the  greater  part  of  their 


THE   CAMBRIAN   SERIES   IN   GEORGIA. 


E251 


weight  intlie  process  ;  their  specific  gravity  liaving  been  re- 
duced from  2.97-3.08  to  1.20,  and,  for  some  varieties,  to 
less  than  1.00.  These  decayed  hornblendic  rocks,  by  the 
action  of  the  weather,  yield  a  strong  red  soil.  The  de- 
cayed mica-schists,  which  still  retain  their  micaceous 
character,  liave  there  been  called  hydro-mica  schists,  though 
distinct  from  those  of  the  Taconian,  with  which  they  have 
been  confounded. 

§  485.  The  uncrystalline  formations  of  Cambrian  and 
Siluro-Cambrian  age,  as  displayed  in  norchwestern  Georgia, 
present,  according  to  the  catalogue  just  cited,  the  folio Aving 
characters.  Above  the  Ococe  slates  and  conglomerates, 
which  are  of  great  but  uncertain  thickness,  is  found  the 
Potsdam  or  Chilhowee  sandstone,  estimated  at  2,000  feet, 
followed  by  the  Knox  group  of  limestones,  sandstones  and 
shales,  (regarded  as  the  representatives  of  tlie  <  'alciferous 
sandrock  and  the  Quebec  group,)  witli  an  aggregate  thick- 
ness of  4,400  feet.  To  these  succeed  thf  Cliazy  limestone, 
GOO  feet ;  the  Trenton  limestones  and  shales.  700;  and  the 
Cincinnati  group,  consisting  of  silicious  limestojH^s  and 
shales,  with  layers  of  red  hematite,  from  200  to  400 ;  making 
in  all  about  8,000  feet  of  sedimentary  strata  from  the  base  of 
the  Potsdam.  These,  by  the  liypothesls  of  Prof.  lUradley, 
become,  in  their  extension  a  short  distance  to  the  south- 
eastward, iransformed  into  the  29,000  feet  of  crystalline 
rocks  which  he  has  referred  to  the  Upper  Potsdam,  Quebec 
and  Ciiicinn:»ti  groups ;  the  intermediate  divisions  l)eing  no 
longer  distinguishalile. 

§  486.  The  arguments  in  favor  of  such  a  hypothesis,  which 
have  been  urged  by  various  writers  on  American  geology 
since  the  times  of  II.  J).  Rogers  and  Mather,  may  be  summed 
up  under  two  heads:  First,  the  ai)i)ai'ent  stratigra])hi('al 
succession  ;  and  second,  thesu^iposed  evi(hmces  of  ti'ansitioii 
from  the  uncrystalline  to  the  ciystalline  rormalioiis. 

The  mode  of  reascming  under  the  fii-st,  as  a])plie(l  to  the 
rocks  of  tlie  Atlantic  belt,  may  be  faii'ly  stated  to  be  as  fol- 
lows :  Having  assumed  the  possibility  of  such  a  transfor- 
mation in  litliological  characters,  and  liaving  taken  for 
granted  that  the  wliole  succession  in  question  is  a  conform- 


252  E.      SPECIAL   REPORT.      T.  STERRV  HUNT,  1875. 


able  one,  without  inversions  or  dislocations,  a  section  is 
constructed  from  some  formation  in  the  paleozoic  series, 
on  the  west  side  of  the  mountain-chain,  and  the  crystalline 
rocks  beneath  which  this  formation  ai)pears  to  pass,  to  the 
eastward,  aresupy)Osed  to  represent  the  succeeding  members 
of  the  paleozoic  series  in  question. 

The  radical  faults  in  this  reasoning  are:  First,  that  it 
overlooks  the  well-established  fact  that  the  i:)revailing 
structure  in  this  mountain-chain  is  what  may  be  described 
as  a  series  of  inverted  folds,  and  of  dislocations,  as  the  re- 
sult of  which  (nt  least  in  its  western  portions)  the  newer 
rocks  dip,  or  seem  to  dip,  eastward  beneath  the  older  ones  ; 
and  second,  that  it  assumes  the  yjoint  to  be  proved,  namely: 
The  possibility  of  the  conversion  of  great  masses  of  sand- 
stone, limestone,  and  shale,  into  feldspathic,  hornblendic 
and  ndcaceous  strata. 

§  487.  The  fallacies  of  the  method  are  strikingly  shown 
in  its  contradictory  results,  as  illustrated  by  the  different 
paleozoic  horizons  to  winch  vai'ious  theorists  of  this  school 
have,  in  turn,  assigned  each  terrane  of  the  Atlantic  belt. 
This  has  been  abundantly  shown  in  the  i)receding  pages,  for 
the  Iluronian  and  the  Taconian.  As  regards  to  the  Mont- 
alban,  the  characters  of  which  are  perfectly  well-defined 
and  jiersisteiit  from  New  Brunswick  to  Alabama,  we  have 
seen  that  Messrs.  Rogers,  from  a  supposed  parallelism  with 
the  paleozoic  rocks  of  Pennsylvania,  assigned  the  Montalban 
of  the  White  Mountains  to  the  lower  half  of  the  true  Silu- 
rian, namely  :  the  Oneida,  M<'diiia  and  Clinton  formations 
of  the  New  York  series.  Logan  subsequently  referred  the 
same  crystalline  terrane  to  the  Devonian  period,  having 
successively  placed  the  Iluronian  in  the  Siluro-Candjrian, 
and  in  the  Candirian :  while  Bi-adley  now  makes  the 
Montalban  rocks  to  embrace  both  of  these  latter,  leaving 
no  place  in  his  scheme  for  the  Iluronian. 

§488.  As  regards  the  secoiul  argument,  that  from  the 
imagined  passage  from  crystalline  to  uncry stall ine  rocks, 
we  need  only  allude,  in  this  place,  to  the  existence  of  beds 
made  up  from  the  ruins  of  the  former,  which  have  been 
supposed  to  show  the  conversion  of  sedimentary  into  crystal- 


CHANGES    FUOxM    LAURENTIAN    To    CAMIUJIAN.     E.  ^^S 


line  strata,  instead  of  the  reverse  process.     This  point  lias 
already  been  illustrated  in  §  184  and  §  413. 

Distinct  from  such  cases,  are  the  statements  ol'  Mather, 
(§  81)  accordiiiu"  to  whom  it  is  possible  to  trace,  ou  the  east 
side  of  the  river  Hudson,  a  gradual  passage  from  the  rocks 
of  the  Champlaiu  division,  across  those  of  the  Taconic  series, 
to  the  crystalline  schists  of  New  England.  This  supposed 
transition  was  however  leased  cm  the  false  assumption  that 
the  Siluro-Cambrian  and  the  Cambrian  or  Upi)er  Taconic 
of  that  region,  are  one  and  the  same  series,  and  that  their  ap- 
parent lithological  dilTcreuces  are  due  to  the  commencement 
of  a  metam(U'phosis,  which  is  still  further  seen  in  the  marbles 
and  schists  of  the  Taconian,  and  reaches  its  highest  i)<»int 
in  the  crystalline  terranes  further  to  the  east.  It  will,  how- 
ever, be  evident  from  what  has  gone  before,  that  these 
different  types  of  strata  are  not,  as  was  imagined  l)y  Mather, 
the  result  of  subse(xuent  and  unlike  changes  which  one  and 
the  same  uncrvstalline  paleozoic  series  has  suffered  in 
different  geographical  areas  ;  but  that,  on  the  contrary,  they 
belong  to  successive  periods  in  paleozoic  ami  eozoic  time. 

The  great  divisions  of  the  latter,  as  set  foith  in  §  409, 
present,  in  ascending  order,  a  progressive  change  in  mineral 
characters,  the  nature  of  which  has  been  shown  in  §  405, 
406 ;  thus  constituting  a  veritable  passage,  in  time,  from  the 
granitoid  Ottawa  gneiss  at  the  base  of  the  Laui-entian, 
through  the  internKxlia  te  Iluronian  and  Montal  1  )an  divisions, 
to  the  less  markedlv  crystalline  schists  of  the  Taconian. 
The  important  question  of  the  genesis  of  the  crystalline 
rocks  will  be  discussed  in  another  place,  but,  in  tlie  mean 
time,  an  outline  of  the  writer's  views  may  be  found  in  the 
preface  to  the  second  edition  of  his  Chemical  and  Geological 
Essays,  j)ages  xxvii-xxxi. 


Second  Geological  Survey  of  PEiNnsylvania. 


REPORTS  FOR  1874,  1875,  1876,  1877,  AND  1878. 


The  I'oUowiniif  Reports  ure  issued  for  tlio  State  liy  the  Boiird  of  Cominia- 
niissioiicrs,  at  irarrishnru  and  tlie  prices  iiave  been  fixecl  as  foUows,  in  a(^ 
cordance  witli  tlie  terms  of  die  a(!t: 


PRICES  OF  REPORTS. 

A.  Historical,  Sketch  of  GEoi.oGiCAii  Explorations  in  Pennsylvania 
and  otlier  States.  By  .1.  P.  Lesley.  With  appendix,  containing  Annual 
Reports  for  1S74  and  1875 ;  pp.  22(3,  8vo.  Price  in  paper,  ^  2o ;  posttige,  §0  06. 
Price  in  elotli,  ?0  50;  iiostage,  §0  10. 

IJ.    PUELIMINAUY    REPOUT   OP    THE    MINERALOGY   OF    PENNSYLVANIA — 

1874.  Hy  Dr.  F.  A.  Gonth.  With  appendix  on  the  hydro-carbon  compounds, 
by  Samuel  P.  Sadtlcr.  8vo.,  jip.  20(>,  •\vitli  muj)  of  the  State  for  reference  to 
counties.  Price  in  i)aper,  ?0  50;  postage,  §0  OS.  Price  in  cloth,  $0  75;  post- 
age, fO  10. 

B.*  Preliminary  Report  of  the  Mineralogy  of  Pennsylvania  for 

1875.  By  Dr.  F.  A.  Genth.    Price  in  jiajier,  §0  05 ;  i)ostage,  SO  02. 

C.  RuPORT  op  Progress  on  York  and  Adams  Cointies.  By  Persifor 
Frazcr,  Jr.  8vo.,  pp.  lOS,  illustrated  by  S  maps  and  si'cfion.s  and  other  illus- 
trations. Price  in  paper,  $0  85;  postage,  ?0  10.  Price  in  clotii,  ?1  10;  post- 
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CC.  Report  of  Progress  In  the  Counties  of  York,  Adams,  Cum- 
berland, AND  Franklin.  Illustrated  by  •ynops  and  cr ess-sect io7is,  sliow- 
ing  the  Magnetic  and  ^Micaceous  Ore  Belt  near  the  Avestern  edge  of  the  Meso- 
zoic  Sandstone  and  the  two  Azoic  systems  constituting  the  mass  of  the  South 
Mountains,  Avitli  a  preliminary  discussion  on  the  Dillshurg  Ore  Bed  and 
catalogue  of  specimens  collected  in  1S75.  By  Persifor  Frazer,  Jr.  Price,  ?1  25 ; 
postage,  ?0  12. 

D.  Report  opProqrkss  in  the  Brown  Hematite  Ore  Ranges  of  Le- 
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aud  Foglcsville.  By  Frederick  Prime,  Jr.  Svo.,  pp.  73,  with  a  contour-line 
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postage,  ?0  0(). 


II.  Report  oFPRocmEssiNTnECLEAUKiELD  and  Jekpehson  District 
OK  TUB  Bituminous  Coal  Fields  of  Western  Pennsylvania.  By  Franklin 
Piatt.  8vo.,  pp.  U90,  illustrated  by  139  cuts,  8  maps,  ami  'Z  aeclions.  Price  in 
paper,  ?1  50 ;  postaj^e,  §0  13.    Price  in  cloth,  51  7.j ;  posUige,  §0  13. 

nil.   llEI'OUT  OF  PUOORESS  IN  THE   CaMBUIA    AND   SOMERSET   DISTRICT 

OF  THE  Bituminous  Coal  Fields  of  Western  Pennsylvania.  By  F.  and 
W.  G.  Piatt.  Pp.  194,  illustrated  with  S4  wood-culs  and  4  maps  and  sections. 
Part  I.  Cambria,    Price,  ?1  00 ;  postage,  ?0  12. 

Illlir.    llia'ORT  OF  PUOOUESS  IN  THE  CAMBRIA  AND  SOMERSET  DISTRICT 

OF  THE  Bituminous  Coal  Fields  of  Western  Pennsylvania.  By  F.  and 
W.  G.  Piatt.  Pp.  348,  illustrateil  by  110  wood-cuta  andO  maps  and  sections. 
Part  II.  Somerset.    Price,  $0  8.5;  postage,  fO  IS. 

I.  Report  of  Progress  in  the  Venango  County  District.  By  .Tolm 
F.  Carll.  With  observations  on  tiie  Geology  around  Warren,  by  F.  A.  Ran- 
dall ;  and  Notes  on  the  Comparative  Geology  of  Nortli-oastern  Oliioand  Xortli- 
western  Pennsylvania,  and  Western  New  York,  by  J.  V.  Lesley.  8  vu.,  pp. 
127,  with  2  ma2JS,  a  long  section,  and  7  cuts  in  the  text.  Price  in  paper,  $0  (U); 
postage,  50  03.     Price  in  cloth,  §0  S.j ;  postage,  ?0  OS. 

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age, ?0  18. 

J,  Special  Report  on  the  Petroleum  of  Pennsylvania,  its  Pro 
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To  which  are  added  a  Map  and  Profile  of  a  line  of  levels  through  Butler, 
Armstrong,  and  Clarion  Counties,  by  D.  .Jones  TjUc;is;  and  also  a  Map  and 
Prolile  of  a  line  of  levels  along  Slippery  Rock  Crook,  by  J.  P.  Lesley.  8  vo., 
pp.  122 ;  5  maps  and  sections,  -a  plate  and  o  cuts.  Price  in  paper,  SO  7.") :  post- 
age, 50  00.    Price  in  cloth,  §1  00 ;  postage,  ?0  OS. 

K.  Report  on  Greene  and  Washington  Counties— Bituminous  Coal 
Fields.  By  J.  .1.  Stevenson,  8  vo.,  pp.  420,  illustrated  by  4  sections  and  2 
county  maps,  showing  tlio  depth  of  Iho  Pittsburg  and  Wayiiesburg  coal  lied, 
beneatli  the  surface  at  numerous  points.  Price  in  paper,  50  (m  ;  postage,  50  10. 
Price  in  cloth,  gO  90;  postage,  50  IS. 

KK.  Report  of  Piiogress  in  the  Fayette  and  Westmoreland  Dis- 
trict  OF   THE    iJITUMINOrS    CoA  L    FIELDS   OF    WESTERN  PENNSYLVANIA. 

By  J.  J.  Stevenson ;  pp.  4:)7,  illustrated  l)y  oO  wood-cuts  and  3  county  maps, 
colored.  Part  I.  Eastern  Allcirliony  County,  and  Fayctio  and  Westmoreland 
Counties,  west  from  Cliestnut  llidge.     Price,  51  40;  postage,  50  20. 

L.  Specie  L  Report  on  the  Coke  Manufacture  op  the  Yougiiio- 
GiiENY  RiVEU  Valley  in  Fayette  and  Westmoreland  Counties,  witli 
Geological  Notes  of  the  Coal  and  Iron  Ore  Bods,  from  .Surveys,  by  Cliarlos  A. 
Young;  by  Franklin  Piatt.  Tw  ,v  Inch  are  append(>(l :  I.  A  Report  on  Methods 
of  Coking,  l)y  .Tohn  Fulton.  II.  A  Report  on  tlio  use  of  Natural  (Jas  in  the 
Iron  .Manufacture,  by  .lolui  B.  Poarsp,  Franklin  Plait,  and  Professor  Sadtler. 
Price,  $1  00;  postage,  50  12. 

M.  Report  op  Progress  in  the  Laboratory  of  the  .Survey  at 
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postaj,^,  50  ().').    Price  in  cloth,  50  75 ;  postage,  50  08. 

N,  Report  of  Progress.  Two  hundred  Tables  of  Elevation  above  tide- 
level  of  tlio  Railroad  Stations,  Sununitsand  Tunnels ;  Canal  Locks  and  Dams, 
River  RilUos,  itc,  in  aiul  around  Pennsylvania ;  with  map.  By  Charles  Allen, 
Price,  50  70 ;  postage,  50  lo. 


(^.  llKPonT  OF  Proobess  in  the  Beavku  River  District  of  the  Bitit- 
MiNous  Coal  Fields  of  Western  Pennsylvania.  By  I.  C.  White;  pj). 
3H7,  illustrated  wltli  3  Ocolopicai  mnp.mii  parts  of  licavor,  IJutlor,  and  All«- 
gliotiy  (bounties,  and  21  plates  of  vertical  sections.  Price,  ?1  40;  postage, 
?0  20. 

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them.'" 

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By  order  of  the  Board, 

JOHN  B.  PEARS  E, 

ISccretary  of  Board. 

Rooms  of  Commission  and  Museum  :  Address  of  Secretary: 

^S3  Market  Street,  Ilarrisbury.  SSS  Market  Street,  liarrisburg. 


I. 

K 

i; 


